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Archive-name: arch-storage/part2
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See reader questions & answers on this topic! - Help others by sharing your knowledge
Rod Van Meter, Joe Stith, and the gang on

Information on disk, tape, MO, RAID and SSD can be found in part 1 of
the FAQ.  Part 2 covers file systems, hierarchical storage management,
backup software, robotics, benchmarking, MTBF and miscellaneous

1.     Standards
1.1.   ANSI X3B5 {None}
1.2.   IEEE Mass Storage System Ref Model (OSSI) {Brief, 6/1/95}
1.3.   ECMA - European Computer Manufacturers Association {None}
1.4.   System Independent Data Format (SIDF)

2.     I/O Related Email Lists

3.     Hierarchical Storage Management
3.1.   Unitree {Brief}
3.1.1. Epoch vs Unitree
3.2.   National Storage Lab {Brief}
3.3.   HIARC {New}
3.4.   Epoch (also known as StorageTek's NearNet) {Brief}
3.5.   Zetaco/NETstor {Brief}
3.6.   R-Squared Infinity IFS 2 {Brief}
3.7.   AMASS
3.8.   Tracer XFS {None}
3.9.   Metior
3.10.  NAStore {Brief}
3.11.  DMF {Brief}
3.12.  FileServ {Brief}
3.13.  Cray Research's Open Storage Manager {Brief}
3.14.  T-mass {None}
3.15.  HP OpenView OmniStorage
3.16.  Platinum NetArchive-HSM {Brief, New}
3.17.  Large Storage Configurations {Brief,New}
3.18.  Unix HSM Vendor List
3.19.  Mainframe
3.20.  PC & PC Server Oriented Packages
3.20.1. HP Optical Jukebox Storage Solution
3.20.2. Chili Pepper Software
3.20.3. Cheyenne ARCserve
3.21.  DATMAN {Brief}
3.22.  Windows NT
3.23.  Other Non-Unix HSM
3.24.  Tapes as Disks {Brief, New}

4.     Backup Software
4.1.   PC-Oriented Backup Packages
4.2.   Unix Packages
4.2.1. Spectra Logic Alexandria
4.2.2. ADSTAR Distributed Storage Manager
4.2.3. NetWorker
4.2.4. BudTool {Brief}
4.2.5. HP OmniBack II {Brief, New}
4.2.6. Workstation Solutions {Brief}
4.2.7. Amanda {Brief, New}
4.2.8. Remote Backup or Mirroring {Brief, New}

5.     Tape and Autochanger Management Software
5.1.   REELlibrarian
5.2.   ANT Medium Changer
5.3.   Tapes 3000 {Brief}
5.4.   Others

6.     Robotics (Autochangers, Jukeboxes, Stackers, Libraries)
6.1.   8mm {Brief}
6.1.1. Exabyte {Brief} EXB-10h EXB-210 EXB-220 EXB-440/480 EXB-10 EXB-10i EXB-10e EXB-120
6.1.2. ADIC {Brief, New}
6.1.3. Storage Tek (was Lago) DataWheel {Brief}
6.1.4. ACL {None}
6.1.5. Cambridge On-Line Storage {Brief}
6.1.6. Spectra Logic {Brief}
6.1.7. Qualstar {Brief}
6.2.   3480
6.2.1. StorageTek {Brief}
6.2.2. EMASS (was GRAU) {Brief}
6.2.3. 3590 (Magstar,NTP) {Brief}
6.3.   4mm {Brief}
6.3.1. Cambridge On-Line storage {Brief}
6.3.2. Spectra Logic {Brief}
6.3.3. HP 4mm {Brief}
6.3.4. Storage Tek Datawheel {Brief}
6.3.5. Diverse Logistics Libra {Brief, New}
6.3.6. Qualstar {Brief, New}
6.3.7. ADIC {Brief, New}
6.4.   VHS {Brief}
6.4.1. MountainGate (was Metrum)
6.5.   Digital Linear Tape (DLT) (Quantum) {Brief}
6.5.1. TZ877 {Brief}
6.5.2. TL820 {Brief}
6.5.3. MountainGate
6.5.4. Breece Hill {Brief}
6.5.5. Odetics {Brief}
6.5.6. MediaLogic ADL
6.5.7. ADIC {Brief, New}
6.6.   D-2
6.6.1. Ampex
6.6.2. Odetics
6.7.   ID-1
6.7.1. Sony DMS, PetaSite {Brief}
6.8.   Optical Disk (MO,WORM) Libraries
6.8.1. Hitachi 448 GB optical library
6.8.2. HP MO Autochangers
6.8.3. Maxoptix MO Autochangers
6.8.4. MountainGate {Brief}
6.8.5. DISC DocuStore {Brief}
6.8.6. Kodak {Brief}
6.8.7. Sony {Brief}
6.9.   CD-ROM Jukeboxes
6.9.1. Pioneer
6.9.2. CyberTower {Brief, New}
6.9.3. NSMJukebox {Brief, New}
6.9.4. Nakamichi {Brief, New}
6.9.5. CDI Juke Box Library {Brief,New}
6.9.6. K & S M-200 {Brief, New}
6.9.7. DISC {Brief, New}
6.9.8. Meridian {Brief, New}

7.     File Systems
7.1.   NFS {Brief}
7.1.1. NFS V3
7.2.   AFS {Brief}
7.3.   DFS {Brief}
7.4.   Log based file systems
7.5.   Mainframe File Systems
7.6.   Parallel System File Systems
7.7.   Microsoft Windows NT {Brief}
7.8.   Large Unix File Systems
7.9.   Non-Unix Large File Systems

8.     (Device) Interfaces
8.1.   SCSI {Full}
8.1.1. Single ended vs differential
8.1.2. Asynchronous vs Synchronous Transfers
8.1.3. SCSI-I vs SCSI-II vs SCSI-III
8.1.4. Fast-Wide SCSI
8.1.5. Shared Busses / Performance {Brief}
8.1.6. Cabling/Hot Plugging {Brief}
8.1.7. Third Party Transfers/Separation of Control & Data Paths {Brief}
8.2.   IDE {Brief}
8.3.   IPI {None}
8.4.   HIPPI {Brief}
8.4.1. HIPPI-6400 {Brief}
8.5.   Ultranet {Brief}
8.6.   Ethernet {Brief}
8.7.   FDDI {None}
8.8.   Fibre Channel Standard (FCS)
8.9.   ESCONN/SBCON {Brief}
8.10.  IEEE P1394 (Serial Bus)
8.11.  Serial Storage Architecture (SSA)
8.12.  S2I: IEEE P1285 Scalable Storage Interface
8.13.  Multibus, Unibus, Mainframe Channels, and other history {None}

9.     Other
9.1.   Video vs Datagrade tapes {brief, 5/94}
9.2.   Compression

10.    Benchmarking

11.    Mass Storage Conferences
11.0.1. THIC Tape Head Interface Committee {Brief, New}

12.    MTBF (Mean Time Between Flareups, er, Failures)

13.    Mass Storage Reports

14.    Network-Attached Peripherals {Brief}

15.    Other References
15.1.  Print
15.2.  Web
15.3.  Newsgroups
15.4.  Research Papers


17.    Original Author's Disclaimer and Affiliation:

18.    Copyright Notice

19.    Additional Topics to be added
Subject: [1] Standards
From: Standards

There's a killer supply of computer-related standards at Fibre Channel and several
mass-storage-related items can be found there.

The ANSI and IEEE standards can be purchased in hardcopy form (the
only way some of them are available) from Global Engineering
Documents, (800)854-7179 or (303)792-2181.

Subject: [1.1] ANSI X3B5 {None} From: Standards
Subject: [1.2] IEEE Mass Storage System Ref Model (OSSI) {Brief, 6/1/95} From: Standards The Storage Systems Standards Working Group now has a WWW page at Version 5 of the model is available via as the files{1,2,3}. The OSSI (Open Storage Systems Interconnection) Reference Model (its new name) "provides the framework for a series of standards for application and user interfaces to open storage systems." One of its prime purposes is to define a common vocabulary. Claiming compliance with the model at the moment has little practical value as far as interoperation of different pieces from different vendors goes (which is one of the ultimate aims of the still-distant standards that may develop from this model).
Subject: [1.3] ECMA - European Computer Manufacturers Association {None} From: Standards
Subject: [1.4] System Independent Data Format (SIDF) From: Standards This is a data format for tapes and removable disks, to facilitate interchange between hardware and software platforms. See the FAQ at
Subject: [2] I/O Related Email Lists From: I/O Related Email Lists Here is a list of email reflectors for those who need to be deeply involved in the technical details of various interfaces and standards. X3T10/95-010 r0 April 6, 1995 I/O Interface Related Reflectors (mailing lists) Subscribe/ majordomo/ Reflector Unsubscribe Broadcast to listserv Name Address Reflector keyword ------------- -------------------- ------------------------ ----------------- SCSI scsi-request@symbios n/a (human) .com ATA ata ATAPI atapi SSA ssa IDETAPE idetape Disk Attach disk_attach 10bit 10bit CD-Recordable cdr System Issues si MultiMedia mmc IEEE P1394 bob.snively@eng.1. n/a (human) com SFF bob.snively@eng.1. n/a (human) com IPI ipi-ext HIPPI hippi-ext Fibre Chan. fibre-channel-ext@think. fibre-channel-ext com FC IP Prot. fc-ip-ext PCMCIA pcmcia-gen FC Class 4 majordomo@northyork. fc-class4 FC Isoch. majordomo@northyork. fc-isoch@northyork.hp. fc-isoch com All of the majordomo and listserv reflectors are automatic. To subscribe or unsubscribe, send a message to the subscribe/unsubscribe address with a line in the message body (not the subject line) of the following format: command reflector_name [your_email_address] NOTE: At least for the reflectors at, your email address is optional. If you include it and it doesn't match the address in the email headers, there will be a delay while humans verify your email address. examples: subscribe ata subscribe ssa subscribe ssa subscribe atapi subscribe mmc subscribe fibre-channel-ext subscribe pcmcia-gen unsubscribe ssa help lists The other reflectors are managed by humans who are a little less picky about the request format, but not quite as prompt. Please include your name, email address, phone, and fax numbers in the message body for the human-managed reflectors. (with permission from John Lohmeyer, 95/5/10)
Subject: [3] Hierarchical Storage Management From: Hierarchical Storage Management HSM systems transparently migrate files from disk to optical disk and/or magnetic tape, usually robotically accessible. Then when files are accessed by a user, they transparently move them back to disk. Watch for maximum file size limitations, sometimes limited by the size of the media used, sometimes by the server's OS, and sometimes neither. Some offer integrated backup. Some will manage multiple copies of files for data reliability. Some offer integrated migration from other systems (ie, file servers and/or workstations) to the central location disks, then to the central location robotics. This generally requires changes to the on-disk file system format on the migration clients. An item to watch for is that the file management may be exactly like Unix -- that is, all files appear to be online, and once they're deleted, they're gone forever, even though the data may still be on tape. All of the subsections here are Unix-compatible (in various flavors) unless indicated otherwise. Additional Information: See also _DEC Professional_, February 1993, Page 40 and _Client/Server Today_, Dec. '94, p. 60. The System-Managed Storage Guide by Howard W. Miller, $225 for first copy, $75 for additional copies for same company available from The Information Technology Institute, 136 Orchard Street, Byfield, Massachusetts, 01922-1605. ( Thomas Woodrow did an evaluation of NAStore, FileServ, DMF and Unitree in 1993. It can be obtained through or the Proc. 3rd NASA Goddard Conference on Mass Storage Systems and Technologies, Oct. 1993, pp. 187--216. Somewhat dated now but excellent methodology for comparing HSMs.
Subject: [3.1] Unitree {Brief} From: Hierarchical Storage Management The uncle of UNIX HSMs. Developed primarily at Lawrence Livermore National Laboratories. Commercialized by a company called DISCOS, then sold to OpenVision. UniTree was sold to UniTree Software in December, 1994. See Many versions exist on different hardware platforms, including a National Storage Lab (NSL) UniTree commercialized by IBM - Fed Systems. It's also available on SGI, Convex, and Amdahl hardware, at least. See also "Epoch vs Unitree" below For Convex, try Jim Wilson 214-497-3085 Business Development Data Management Applications Convex Computer Corporation For most other platforms, call Open Vision at (800)223-OPEN or (510)426-6400. New info: The latest release of UniTree, V1.9.1, has the following changes: - Available directly from UniTree Software Inc. - Support DEC, HP-UX, SGI, Sun - GUI(Tcl/Tk) tools for installation and administration - New name database structure - Common Message Logger - Parallel Migration and Staging - Multiple Storage Hierarchy (Optical/Tape) - FTP performance improvements (Read/Write 20MBs/16MBs)* - NFS performance improvements (Read/Write 3.5MBs/2MBs)* - Rule-based dynamic migration - Support for new robots (e.g., STK 97xx) - Support >2GB disk partitions on Sun - 64K File Families - Configurable media and drive types - Departmental File Server Configuration - Compatible with most backup software (Legato, CAM, SMArch) Demo copy available for download from web site: New resellers in Asia, Europe, Australia * Measured on a dual cpu Sun Ultra3000 with 256MB and 10 disks -- Francis Kim Phone: (510) 833-3460 Director of Sales and Marketing FAX: (510) 833-9345 Unitree Software, Inc. e-mail: 11875 Dublin Blvd. Suite A200E WWW: Dublin, Ca. 94568
Subject: [3.1.1] Epoch vs Unitree From: Hierarchical Storage Management (Note: this evaluation is old, and should be taken with a grain of salt. rdv, 3/96) (6/93) We just bought both last year. We bought an Epoch I with the 20 GB EO and 327 GB worm. We will be upgrading it to an Epoch II soon. We also bought Unitree from Titan to run on a Silicon Graphics server and hook up to the STK 3480 silo. We hope to add more silos eventually. Unitree is licensed based on storage capacity while Epoch is not. There may be an exception to this - STK just began reselling Epoch as the front end for their silos and I'm not sure how they handle licensing. My office mate and I (I handle Epoch, he handles Unitree) have enjoyed comparing the merits/demerits of each over the last year. Comparison in our case is slightly slanted due to the fact that the Epoch has optical disk while the Unitree system has 3480 tape - so some observations have more to do with media advantages/disadvantages. Unitree + Allows large files - can span volumes + Allows you to enlarge the cache easily, allows very large cache +- Unitree has replaced several UNIX utilities with their own (FTP, NFS and the file system). This allows certain features to work but is generally slower and disallows access to the archive when you are on the server itself - unless you NFS mount! + Allows deleted files to be saved for a specified time + Allows multiple copies of files to be kept + Data is copied to archive soon after creation + Unitree runs on several different platforms - Does not allow access to data until it is completely reloaded - Behaves poorly with small files (due to necessary overhead) - Unitree is licensed to several vendors, so versions differ - NFS access is so slow that we recommend it not be used for file transfer - only for ls and du, etc. Use FTP. - The Silicon Graphics version is still new and has some problems Epoch + Allows access to the data as soon as part of it is loaded + Company seems serious about reputation and support + The Epoch II is based on a SUN system, with few modifications + Data is copied to archive only when the cache space is needed + All native UNIX transfer methods work - NFS, FTP and RCP + Add on products greatly simplify backup and extend archiving features to other systems. - Deleted files are gone forever - Currently only available on SUN. This will change. - Cannot span volumes yet - limiting file size - Has the SUN limitation of 2 Gb per filesystem. This would be a bigger problem if you used it for a 3480 silo. {Note 2GB of Magnetic Disk limit, not the entire HSM store} - Behaves poorly with small files (due to necessary overhead) - Since inodes are kept on magnetic cache, you must take into account the maximum number of files you will ever need. - Since inodes are always on disk, certain disk operations can take forever since all inodes must be examined. - Enlarging a magnetic disk filesystem which has associated archive media requires you to offload all data and then reload it. If anyone has found another way, I would like to hear about it. {Others did offer some easier work-arounds} In all fairness to Titan, they have been addressing any problems and it has been improving. Epoch too plans to address some of their shortcomings. We are looking forward to growing with both products. The likelihood that the various flavors of Unitree will standardize depends on what happens with Discos. My guess is that some features/enhancements will be filtered back to the base product released by Discos. Bye... (,, Tom Bodoh, USGS/EROS Data Center, Sioux Falls, SD)
Subject: [3.2] National Storage Lab {Brief} From: Hierarchical Storage Management NSL is an industry consortium (American companies only) that has a version of Unitree, and is creating their own new High Performance Storage System. HPSS, among other features, supports striping of removable media, and full 64-bit files. Some of the work is being done at LLNL, where UniTree was originally developed. There's a good overview reachable at (rdv,95/1/12)
Subject: [3.3] HIARC {New} From: Hierarchical Storage Management HIARC HSM runs on Solaris 2.4 and above. Slides in at the vnode layer. Supports 4mm, 8mm, 3480, DLT, VHS, D-1 and D-2 tape drives, and appropriate robotics (I don't have a specific list). Removable media formats are standard (_which_ standard, I don't know). Pricing from $4k to $25k is reasonable for the functionality. See (rdv, 97/3/20)
Subject: [3.4] Epoch (also known as StorageTek's NearNet) {Brief} From: Hierarchical Storage Management See also "Epoch vs Unitree" in Appendix
Subject: [3.5] Zetaco/NETstor {Brief} From: Hierarchical Storage Management NETstor can be reached at NETstor, Inc. (formerly Zetaco, Inc.) is a leading provider of hierarchical online mass-storage systems for open systems. Primarily NFS accessable systems with magnetic disks and optical-disk libraries. They have marketing agreements with Digital Equipment Corp, and Hewlett-Packard. ( Netstor was bought by Cheyenne, and is now sold by them (, 10/95).
Subject: [3.6] R-Squared Infinity IFS 2 {Brief} From: Hierarchical Storage Management Contact: Steve Wine, Manager, Mass Storage Products, R-Squared, 11211 East Arapahoe Rd, Englewood, CO 80112, 303/799-9292 or FAX 303/799-9297
Subject: [3.7] AMASS From: Hierarchical Storage Management From Advanced Archival Products. Supports a huge range of devices, autochangers, and operating systems. Block-based movement of data between the hard disk cache and tape or optical tertiary storage. Systems run from a few gigabytes up to at least 12 TB, with prices dependent on capacity. New versions allow multiple cache disks. Slips right in to the VFS layer and looks like a normal Unix file system, with the plusses and minuses that entails. No file versioning or multiple copies yet. File creation is an Achilles' heel on performance. Since it's block based, files can be larger than a piece of media. Separate product DataMgr will migrate files from client machines to the AMASS server automatically (with FS changes, of course). AMASS is now owned by EMASS, and you can find info at (rdv, 1996/3/27)
Subject: [3.8] Tracer XFS {None} From: Hierarchical Storage Management
Subject: [3.9] Metior From: Hierarchical Storage Management Metior (pronounced like meteor) is targetting an incredibly broad market, from laptops with removable media through supercomputers, with prices from $650(!) to $118K. They handle multiple coordinated copies, so off-site backup can be automatic. Can do migration for client machines (with appropriate software licenses and changes to the file system). The hierarchy seems to be extremely flexible, variable on a per-user or per-group basis. Machines without client licenses can mount the Metior FS using NFS. Runs on Suns, SGI, and HP 9000/700. ANT is new, and they've only got a handful of customers so far, but it looks _very_ interesting. (info from, written by rdv, so it's my fault if it's not accurate) (rdv,94/7/7) More information available on the WWW FAQ version. Also see them at Automated Network Technologies 3333 South Bannock Street, Suite 945 Englewood, CO 80110 USA Phone 303.789.2506 FAX 303.789.2438 Email
Subject: [3.10] NAStore {Brief} From: Hierarchical Storage Management NAStore is a Unix migrating file system developed by the Numerical Aerodynamic Simulation program at NASA Ames. It is available through NASA's software distribution agency, COSMIC. It currently runs only on Convex with 34x0 cartridges and Storage Tek robots. Looks like a local file system to users of the Convex. Available with source. Info on NAStore can be found on the web at COSMIC's address is : University of Georgia 382 East Broad Street Athens, Georgia, 30602-4272, US 011-706-542-3265 For more information on NAStore, contact John Lekashman, (info from Bill Ross,, 94/9/15)
Subject: [3.11] DMF {Brief} From: Hierarchical Storage Management Cray Research's Data Migration Facility. The grandaddy of Unix HSM systems. You can find info on DMF at, or call +1 612 683 3897 or email It's reportedly running on more than 200 systems, and development is continuing. Large users are in the hundreds of TB, with millions of files and >1TB/day through DMF. Information from: "Storage Management at Cray Research, Inc", Metcalfe, D.J. and Thompson. D. "Data Migration Facility Development Update", Lazatella, T.W. and Bannister, N. Cray User Group, Barcelona, 1996, in press. (, 1996/4/2)
Subject: [3.12] FileServ {Brief} From: Hierarchical Storage Management From E-Systems. Works with the E-Systems ER-90 (D-2) tape drive and Odetics robots, as well as 3480 with the Storage Tek ACS 4400. Runs on Convexes (only?). Supports multiple copies of files. Retrieves only necessary info from tape to disk before completing request. Reportedly no longer available on Convex, in beta test on SGI (, 10/95) Now owned by EMASS, info at
Subject: [3.13] Cray Research's Open Storage Manager {Brief} From: Hierarchical Storage Management They have some agreement with Legent Corporation. OSM runs on Sparc machines, including the Cray Superservers. Price ranges from $500 to $5,000, which is very cheap for HSM. However, it might only be capable of migrating among disks -- I don't see any mention of autochangers. (rdv, 94/12/9)
Subject: [3.14] T-mass {None} From: Hierarchical Storage Management
Subject: [3.15] HP OpenView OmniStorage From: Hierarchical Storage Management Supports multiple types of tertiary media (optical, tape) though it seems to come originally from their work for their own MO jukeboxes. Supports multiple types of clients. (info from Herbert Volk <>, 1995/9/28) More info available at Now a very broad storage management suite, covering lots of functionality for management. Supports MO, DLT and 8mm as media, though only a limited number of autochangers. (rdv, 98/1/16)
Subject: [3.16] Platinum NetArchive-HSM {Brief, New} From: Hierarchical Storage Management Used to be ASC (Advanced Systems Concept) before being bought by Platinum. Runs on SunOS, HP, and Domain/OS. Supports numerous optical jukeboxes. See (rdv, 96/4) PLATINUM technology, inc. 1815 South Meyers Road Oakbrook Terrace, IL 60181 1-800-442-6861 -or- 708/620-5000 e-mail:
Subject: [3.17] Large Storage Configurations {Brief,New} From: Hierarchical Storage Management describes their Solaris-based HSM product. Only one computing platform, but a reasonably broad range of mid- to high-end peripherals and robotics supported, from little Exabyte autochangers to the IBM 3494 and STK silos. (rdv, 96/7/23)
Subject: [3.18] Unix HSM Vendor List From: Hierarchical Storage Management This list is adapted from _Client/Server Today_, Dec. '94, with some of my own additions. All the phone numbers are USA (apologies to international readers for the 800 numbers, but they're all I've got). I don't know anything about some of these companies; I suspect some of them work with HSM from other vendors rather than their own packages. I've indicated on the list various reports of companies OEMing from each other; this is not out of disrespect for the work involved in OEMing/supporting or porting such complex software, but an attempt to divide the HSM vendors into "families" with similar capabilities (occassionally on very disparate platforms). Vendor Product Contact ------ ------- ------- Advanced Archival Products AMASS (303)792-9700 * Advanced Software Concepts (ASC) (619)737-9544 Alphatronix ASC (919)544-0001 Artecon ASC (619)931-5500 AT&T CommVault DataMigrator (908)935-8000 Automated Network Technologies (ANT) Metior (303)789-2506 * Computer Associates International (800)225-5244 Computer Upgrade (808)874-8807 Convex Computer UniTree (214)497-3085 * COSMIC (NAStore) (706)542-3265 + Cray Research DMF (800)BUY-CRAY * Digital Equipment (DEC) NETstor (800)344-4825 Dorotech (703)478-2260 Epoch Systems (508)836-4300 * E-Systems FileServ ?* File Tek Storage Machine (301)251-0600 Fujitsu Computer Products of America OSM (408)432-6333 Hewlett-Packard OmniStorage* ,NETstor (800)637-7740x8509 HIARC (714)253-6990 IBM UniTree (800)225-5426 Introl (612)788-9391 Large Software Configurations (LSC) (612)482-4535 * Legent $OSM (703)708-3000 National Storage Lab (NSL) HPSS +* NETstor (Cheyenne) $NETstor (612)890-9367 (OpenVision UniTree (510)426-6400 *) Platinum NetArchive HSM (708)620-5000 * Qstar Technologies (301)762-9800 Raxco (301)258-2620 Software Partners/32 (508)887-6409 Storage Technology (STK, StorageTek) (303)673-5151 T-mass ? Tracer XFS ? UniTree Software UniTree (510)833-9344 * * = Info elsewhere in FAQ + = not commercial product ? = no contact info $ = original developer (no mark indicates OEM)
Subject: [3.19] Mainframe From: Hierarchical Storage Management IBM also has HSM for MVS, called, imaginatively, HSM. There is the storage home page. I have also found references to System Managed Storage SMS and HSM and DFHSM (Data Facility Hierarchical Storage Manager) but could find no online information. There are probably manuals like DFHSM Version 2 Release 5.0, General Information manual (GH35-0092) if you are a real glutton for punishment and have a friend at ibm. So we have ADSM and DFHSM and DFSMS and probably others. But not much online information. Sorry. A little searching from the might turn up something too. (Del Cecchi, <dcecchi@VNET.IBM.COM>, 1996/3/27)
Subject: [3.20] PC & PC Server Oriented Packages From: Hierarchical Storage Management
Subject: [3.20.1] HP Optical Jukebox Storage Solution From: Hierarchical Storage Management Netware 3.11 based, up to 10.4 Gigabytes, includes model 10LC optical jukebox which has one drive and 16 disks each with 650 MB formatted capacity. Hewlet-packard (Palo Alto, CA) 800/826-4111.
Subject: [3.20.2] Chili Pepper Software From: Hierarchical Storage Management A company from Atlanta, GA named Chili Pepper Software (404-339-1812) and 3M have gotten together in some fashion to make HSM software for PCs using QIC. (rdv, 94/9/5)
Subject: [3.20.3] Cheyenne ARCserve From: Hierarchical Storage Management Runs on Netware servers. Transparent to most clients, but has a neat feature: if you use a special TSR and DLL on client PCs, when it has to retrieve a file from secondary or tertiary storage, it can give you an estimated retrieval time and the option to abort. (516)484-5110, (800)243-9462. (rdv,95/02/14)
Subject: [3.21] DATMAN {Brief} From: Hierarchical Storage Management Simple HSM for 4mm tape drives under MS-DOS. A limited freeware version is available. More info at Voice: 708-369-7112 Fax: 708-369-7113 (Kan Yabumoto,, Nov. 1995)
Subject: [3.22] Windows NT From: Hierarchical Storage Management Try: Avail Systems 4760 Walnut St Boulder, CO 80301 voice: +1.303.444.4018 fax: +1.303.546.4219 (Dave Skinner) (95/2/12) Avail's product, NetSpace HSM, has been selected by Microsoft to be incorporated into future versions of NT, and also provides a link between NetWare and IBM's ADSM. NetSpace also runs on Novell NetWare systems. See ("Wight, Risa" <>, 95/10/17)
Subject: [3.23] Other Non-Unix HSM From: Hierarchical Storage Management DEC's old Tops-20 OS supported offline files, and would generate an automatic request to the operator to mount a tape when the user accessed the file. When you listed a directory, it would show you which files were online and which off. DEC's OpenVMS has some sort of support for this now. VMS 6.1 supports "shelved" files. There is also the product Virtual Branches, from Acorn Software, which does HSM for MO and CD-ROM for OpenVMS. Acorn Software, Inc. 267 Cox St. Hudson, MA 01749 voice: (508)568-1618 fax: (508)562-1133 Internet:
Subject: [3.24] Tapes as Disks {Brief, New} From: Hierarchical Storage Management There are several packages around (mostly for PCs) that will let you use a tape drive like a disk drive. Of course, it's _very_ slow unless it uses some disk-based information as well. See for one such product. (rdv, 96/11/4)
Subject: [4] Backup Software From: Backup Software Backup software usually provides some form of management of files, tapes, and autochangers. Retrieval of files is not automatic (as in true HSM). These are designed to allow you to recover from disk or file system failures, and to recover files accidentally (or maliciously) deleted or corrupted. Some work in conjunction with HSM systems, which are often vulnerable to the latter class of problems. I've concentrated here on backup software that supports various autochangers, as this is of more interest to people in this group than standalone software for backing up one hard disk onto one tape.
Subject: [4.1] PC-Oriented Backup Packages From: Backup Software I don't think any of the PC operating systems come with tape support built in, so you have to have some 3rd party software to work with tape. This short list is primarily oriented toward PC servers. It's partly derived from _PC Magazine_, March 29, 1994, pp. 227-272. Note that there has been an ongoing discussion of the pitfalls of Windows 95 and third-party backup software; many in particular are having trouble with long file names. Arcada Software - Storage Exec. (NT) Avail (NT) Cheyenne Software - ArcServe (Netware) Conner Storage Systems - Backup Exec (Netware) Emerald Systems - Xpress Librarian Fortunet - NSure NLM/AllNet Hewlett Packard - OmniBack II (NT) Legato - NetWorker (Netware) Mountain Network Solutions - FileSafe NovaStor (Netware) Palindrome - Network Archivist (Netware, OS/2, Windows) Palindrome -Backup Director Performance Technology - PowerSave (Netware) Systems Enhancement - Total Network Recall Arcada is at 800/327-2232 and at {Under Construction}(SHMO)
Subject: [4.2] Unix Packages From: Backup Software Some people claim "Unix tape support is an oxymoron," so there's a big market in outdoing tar, dump, dd and cpio. APUnix - FarTool Cheyenne - ArcServe (see under PCs, above) Dallastone - D-Tools Delta MicroSystems (PDC) - BudTool Epoch Systems - Enterprise Backup IBM - ADSM (Adstar Distributed Storage Manager) Hewlett Packard - OmniBack II Legato - Networker Network Imaging Systems Open Vision - AXXion Netbackup 2.0 Software Software Moguls - SM-arch Spectra Logic - Alexandria Workstation Solutions {Under Construction}(SHMO)
Subject: [4.2.1] Spectra Logic Alexandria From: Backup Software Spectra Logic makes 4mm & 8mm autochangers, but this software supports other autochangers as well. Has a nice feature that it claims to be capable of backing up live Oracle, Informix and Sybase databases. email (rdv,95/2/14) On the web at
Subject: [4.2.2] ADSTAR Distributed Storage Manager From: Backup Software Runs on everything from OS/2, AIX and OS/400 to VSE/ESA, MVS and VM providing backups for virtually everything you can think of in PCs and workstations. (800)IBM-3333 or anonymous ftp to (rdv,95/2/14) or
Subject: [4.2.3] NetWorker From: Backup Software Backup software. See Runs on a wide variety of platforms and supports a bunch of types of autochangers. Legato Systems, Inc. 3145 Porter Drive Palo Alto, CA 94304 Phone: 415-812-6000 Fax Number: 415-812-6032 Fax-on-demand: 415-812-6156
Subject: [4.2.4] BudTool {Brief} From: Backup Software PDC Engineering 111 Lindbergh Avenue Suite C Livermore, CA 94550 USA (510) 449-6881 FAX (510) 449-6885 See
Subject: [4.2.5] HP OmniBack II {Brief, New} From: Backup Software HP's OmniBack II runs on several different platforms, and splits the functionality up. The Backup manager appears to run only on NT, but it can use devices attached to various flavors of Unix, and backs up ten different kinds of Unix and PC clients. Now marketed jointly with OmniStorage, their HSM system, in a (sales) program they call OpenView. See (rdv, 98/1/16)
Subject: [4.2.6] Workstation Solutions {Brief} From: Backup Software See Runs on a variety of Unix platforms, and supports a reasonably broad range (20GB-5TB) of autochangers and tape systems (4mm, 8mm, DLT, VHS). (rdv, 96/7/8)
Subject: [4.2.7] Amanda {Brief, New} From: Backup Software Subscribe to and for some time. The "current" distibution of Amanda seems to be from, with version A very good backup system, with no dollar investment. (David Olsen, <>, 1/23/97) You'll also find a FAQ on it at
Subject: [4.2.8] Remote Backup or Mirroring {Brief, New} From: Backup Software It's now possible, in several fashions, to backup systems over a network or even a modem, for recovery from fires and even disk crashes. Channel extenders, such as the CHANNELink from CNT and the Symmetrix Remote Data Facility, are used by some mainframe systems to create remote copies of disks (remote mirroring) as a disaster recovery measure. Early systems used dedicated fibre or telephone lines and ran proprietary communications protocols. Newer systems from CNT are capable of communicating over general-purpose wide-area networks, thus saving the costs of the dedicated lines. It's also possible to backup PCs over your modem in an incremental fashion, through your ISP; one example is Two other companies that do this over the Internet (out of, I believe, more than 30) are Connected Corp., Framingham, MA; Virtual Technology Corp., Minneapolis, MN.
Subject: [5] Tape and Autochanger Management Software From: Tape and Autochanger Management Software This category of software can overlap with both HSM and backup, above, and basic tools are often available from the autochanger hardware vendors, below. New additions to this category welcome -- I'm sure there are numerous vendors I don't know. Functionality varies widely, from rudimentary "move the cartridge" interfaces to sophisticated tape-tracking databases. (rdv, 95/6/1)
Subject: [5.1] REELlibrarian From: Tape and Autochanger Management Software Actually a whole set of software tools from Storage Tek, available through Software Clearing House, Manages different types of media for you, including 3480 in STK silos, under MVS or Unix. (rdv from, 95/6/1)
Subject: [5.2] ANT Medium Changer From: Tape and Autochanger Management Software There is a public version of a Solaris 2.x Medium Changer driver with a set of command line utilities in our FTP server. Only restriction is that you cannot bundle it with another product or resell it (intended for end-user use only). or (Tim Sesow, ANT, 1995/9/21)
Subject: [5.3] Tapes 3000 {Brief} From: Tape and Autochanger Management Software Tapes3000 is a UNISON/TYMLABS product that puts a label on a reel tape, DDS, any kind of media storage and adds it to a "tapes database" so you do not have to manually log and label backup tapes or special request tapes, and possibally make a mistake. You can also use this for unlabeled media, but then you would have to manually log the media. You are able to set a "dataset" for differrent retentions (Generations, weekly, monthly, daily etc). Then when those criteria are met the program will automatically scratch those tapes, then you run a report and it will give you a list of what scratched for that day, week, or whatever time you want to run the job. Tapes3000 is part of a package that you can receive called MAESTRO which is a job scheduler program. Not an autochanger control package, just tape management software. (R Johnson <>, 1996/3/25)
Subject: [5.4] Others From: Tape and Autochanger Management Software Many of the HSM (including EMASS, above, with their VolServ) and backup vendors also sell simple autochanger control interfaces. Check with them. Some things I've read indicate that one or more of the university-based projects ought to have a freely available autochanger controller; if anybody has any info on this let me know.
Subject: [6] Robotics (Autochangers, Jukeboxes, Stackers, Libraries) From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) I use the term "robotics" to refer to access to multiple removable volumes by a fewer number of drives without a person. This includes sequential stackers, as well as random access robotics. A stacker typically is capable of taking (literally) a stack of tapes and putting them into the drive one at a time, in order. No random access to specific tapes, as with a full-function autochanger. Stackers typically are limited to 8-10 cartridges, and are used by people whose backups have exceeded the size of one cartridge. In the larger media formats, such as D-1, D-2, Betacam, etc., the traditional manufacturers of broadcast autochangers, such as Asaca, Odetics, Sony, etc. have products that are easily adaptable to storage use. The August 1996 issue of Byte magazine has an article comparing 12 tape autochangers. It is a little misleading, not mentioning any of the truly large library systems, and only one midrange, whose capacity is quoted assuming DLT 7000 tape drives, which is never mentioned. In addition, much of their testing is more related to the drives than the autochangers.
Subject: [6.1] 8mm {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries)
Subject: [6.1.1] Exabyte {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Phone: 800/EXABYTE, 1685 38th st, Boulder, CO 80301, Fax 303/447-7689. On the web at
Subject: [] EXB-10h From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Current model, 10 cartridges, one drive. Not Mammoth compatible. 70 GB, uncompressed. (rdv,96/8/29).
Subject: [] EXB-210 From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) 2 drives, 11 cartridges, not Mammoth compatible.
Subject: [] EXB-220 From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) 2 drives, 20 cartridges, Mammoth compatible (rdv,96/8/29).
Subject: [] EXB-440/480 From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) 40 or 80 cartridges, 2 or 4 drives, Mammoth compatible. 1.6 TB uncompressed, with Mammoth. (rdv,96/8/29).
Subject: [] EXB-10 From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Ten cartridges, one full-height drive. Original 10 cartridge robot. No robotic intelligence, when one tape comes out, the robot mounts the next tape in sequence (i.e. a kind of stacker). Button selectable to loop back to the first tape or to stop at the end. Discontinued.
Subject: [] EXB-10i From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Ten cartridges, one full-height drive. Released shortly after the EXB-10. Includes SCSI attachment to robotics. Now nearly replaced by the EXB-10e. Discontinued.
Subject: [] EXB-10e From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Ten cartridges, one full-height drive. Announced around 4/93. Includes better control panel and display than EXB-10i. Drive mounted horizontal and tape magazine at slight angle (rather than vice-versa in EXB-10i). Discontinued.
Subject: [] EXB-120 From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Holds 120 8mm cartridges, up to four full-height drives. Discontinued.
Subject: [6.1.2] ADIC {Brief, New} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) I'm not sure if ADIC manufactures or OEMs their robotics, but they apparently sell to end users. They have 8mm, 4mm and DLT autochangers in a variety of small to medium sizes, up to about a terabyte. See (rdv,97/3/18)
Subject: [6.1.3] Storage Tek (was Lago) DataWheel {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Holds 54 8mm tape cartridge in a carousel with 2 8mm drives. The carousels are removable. Now Storage Tek, used to be a small company called LAGO, which apparently no longer exists. You'll find info at: (rdv, updated 1996/3/22)
Subject: [6.1.4] ACL {None} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries)
Subject: [6.1.5] Cambridge On-Line Storage {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Sixty and 240 GB libraries, 713/981-3812
Subject: [6.1.6] Spectra Logic {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Spectra Logic makes SCSI-controlled 8mm and 4mm (DAT) autochangers. One to four drives, with 20 to 60 slots. Capacity currently up to 600 GB of DDS-2 (4mm) or 300 GB 8mm. Early models (STL-6000 & STL-8000) were a rotating carousel. Newer ones use an arm and the tapes don't move. Supported by a variety of software vendors. List prices of $9K (Spectra 4000/20 slots, one DDS-2 drive) to $31K (60 slots with four drives and barcode support) including drives. They also make a thing called TapeFrame, which consists of several of their autochangers working in conjunction, with capacities up to 2.2 TB. U.S.: 1-800-833-1132 or 303-449-6400 (Britt Terry,, 95/1/12) See also under backup software, and on the web at
Subject: [6.1.7] Qualstar {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Makes 8mm libraries that hold 10 to 120 cartridges and 2 to 6 drives. tel:(818)592-0116 fax:(818)592-0061 or (rdv,95/2/14) Our TLS-4000 8mm library family now supports the Sony SDX-300C drive. Production shipments have started and enduser installations have occurred. Early field reports are completely positive. TLS-4000 also supports Exabyte Mammoth and 8505XL drives. (Bob Covey,, 96/10/22)
Subject: [6.2] 3480 From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries)
Subject: [6.2.1] StorageTek {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Storage Tek makes huge autochangers, referred to as silos, round and several (~5) meters in diameter. They hold 6,000 3480-style tapes. At original 3480 densities, that's only 1.2 TB per silo, but capacities have gone up to (I think) 800 MB/cartridge, and are poised for a HUGE jump if Storage Tek gets their Redwood tape drive finished (in beta test, 12/94), up to 20 GB/cartridge, 120 TB/silo. There is a smaller silo, known as WolfCreek, that holds 500-1000 cartridges. STK also OEMs a 3480 autochanger from Odetics. Holds ~260 cartridges, I think, in rotating drum, with room for ?2? tape drives above it. (rdv,95/1/12) However, I couldn't find any info about this on the web site. They also have a web site at (95/5/16,rdv) All but the Odetics (known as Ocean, I think) are Redwood-compatible. The new 9710 (codenamed Panther) can handle both DLT and 3480 cartridges in a mini-tower. (, 1996/3/12)
Subject: [6.2.2] EMASS (was GRAU) {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Grau, a German manufacturer, makes high-end, very large capacity mixed-media autochangers known as the ABBA series, targetted I believe primarily at the IBM mainframe market. (rdv,94/11/7) Bought by EMASS, see They support 3480, D-2, MO, VHS, DLT, 8mm all in one robot, so they renamed the autochanger series the AML, Automated Mixed-Media Libraries.
Subject: [6.2.3] 3590 (Magstar,NTP) {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) MountainGate has announced that they will have, later this year, a 300-cartridge autochanger. IBM of course makes numerous autochangers for NTP; the 3494 and 3495 models both support it. More info at (They probably have smaller libraries, too.) Word in the newsgroup has it that STK robots won't support Magstar due to the rivalry between IBM and STK. (rdv,1996/3/12)
Subject: [6.3] 4mm {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries)
Subject: [6.3.1] Cambridge On-Line storage {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Libraries of 120 and 40 GB, 713/981-3812
Subject: [6.3.2] Spectra Logic {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Spectra Logic makes SCSI-controlled 8mm and 4mm autochangers. See above under 8mm autochangers.
Subject: [6.3.3] HP 4mm {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) I think HP makes their own 4mm autochangers.
Subject: [6.3.4] Storage Tek Datawheel {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) The 4mm version. 25 cartridges, so up to 100GB uncompressed. Info at
Subject: [6.3.5] Diverse Logistics Libra {Brief, New} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Two libraries, the Libra-8 and Libra-16, with 8 or 16 slots (32 or 64 GB uncompressed) and one DAT drive. Info at or (Europe), or ( (Marc SCHAEFER), 96/8/6)
Subject: [6.3.6] Qualstar {Brief, New} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) See We are now shipping our TLS-2000 4mm tape library family. This product line consists of 6 models ranging from 1-2 drives with 18 tapes, to 1-4 drives with 144 tapes. All units include a mailbox and barcode support. I believe that the TLS-24144 is the largest 4mm library in production. TLS-2000 supports Seagate, Sony and HP DDS-2 drives and we are about to start testing the Sony SDT-9000 DDS-3 drive. (Bob Covey,, 96/10/22)
Subject: [6.3.7] ADIC {Brief, New} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) I'm not sure if ADIC manufactures or OEMs their robotics, but they apparently sell to end users. They have 8mm, 4mm and DLT autochangers in a variety of small to medium sizes, up to about a terabyte. See (rdv,97/3/18)
Subject: [6.4] VHS {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries)
Subject: [6.4.1] MountainGate (was Metrum) From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Metrum's data storage division was bought by Lockheed Martin and renamed MountainGate. Autochangers for their VHS-based high-capacity (20GB, 2 MB/sec.) tape drive. They now have a stacker available for standalone drives. Library of 960 GB (RSS-48b) holds 2 drives and 48 cartridges in a rotating drum. Library of 12 TB (RSS-600b) holds 5 drives and 600 cartridges in less than 20 square feet of floor space. The tapes are held in rotating drums on each side, with the drives in a rack in between. OEMs through Convex, IBM, and a host of resellers. Integrated with various backup and HSM packages, including UniTree from Convex & IBM, and AMASS from AAP. See MountainGate also under MO and DLT autochangers. MountainGate A Lockheed Martin Company 9393 Gateway Drive Reno NV 89511-8910 702-851-9393 Phone 702-851-5533 Fax See them on the web at, but as of today (1996/3/19) doesn't have much on the high-end products.
Subject: [6.5] Digital Linear Tape (DLT) (Quantum) {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) T* names are DEC's names, DLT2* names are OEM names.
Subject: [6.5.1] TZ877 {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) One TZ87 tape drive, 7 cartridges, each 10GB native Presumed to be the same as the DLT2700 library. Ref: Digital's Customer Update, March 14, 1994
Subject: [6.5.2] TL820 {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Holds 3 TZ87 tape drives, 264 catridges, five libraries attachable Presumed to be Odetics made (714/774-5000) About $150K U.S. Ref: Digital's Customer Update, March 14, 1994
Subject: [6.5.3] MountainGate From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) At Comdex '94 in Vegas, Metrum (now MountainGate) introduced the D-900 (900 cartridges, up to 20 drives, 9TB uncompressed for DLT-2000) and D-360 (360 cartridges, up to 8 drives, 3.6 TB uncompressed for DLT-2000) DLT autochangers. There is an expansion unit with 480 cartridges which may hold two drives. Up to eight D-360 or D-480 units can be connected via passthrough. They also introduced 28 and 60 cartridge DLT autochangers. Customer shipments starting in early '95. See above under VHS for contact info.
Subject: [6.5.4] Breece Hill {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Breece Hill makes two small (28 and 60 cartridges) DLT autochangers. On the web at Breece Hill Technologies, Inc. 6287 Arapahoe Avenue Boulder, Colorado 80303 USA For more Information 1-800-941-0550 or 303-449-2673
Subject: [6.5.5] Odetics {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Odetics makes a series of DLT libraries that hold, in the basic configuration, 3 DLT drives and 264 cartridges. See
Subject: [6.5.6] MediaLogic ADL From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) MediaLogic ADL, Inc. 1965 57th Court Boulder, CO 80301 Voice: 303-939-9780 Fax: 303-939-9745 email: They have desktop autochangers up to 26 DLT cartridges. See also on the web. Also have 4mm and 8mm autochangers that are similar. I don't know if they manufacturer these or OEM them. (rdv, 1996/3/19)
Subject: [6.5.7] ADIC {Brief, New} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) I'm not sure if ADIC manufactures or OEMs their robotics, but they apparently sell to end users. They have 8mm, 4mm and DLT autochangers in a variety of small to medium sizes, up to about a terabyte. See (rdv,97/3/18)
Subject: [6.6] D-2 From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries)
Subject: [6.6.1] Ampex From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Ampex makes their own autochangers for the DST DD-2 tape drive (see part 1 of the FAQ). DST 410 Automated Cartridge Library: Up to 1.2 terabytes capacity (uncompressed) in 7 square feet of floor space. All 3 cartridge (cassette) sizes supported - 25, 75, 165 gigabytes (uncompressed). SCSI Medium Changer Commands or Ethernet NetSCSI protocol. Console mounted configuration. Single unit price: $150K. DST 810 Automated Cartridge Library: Up to 6.4 terabytes (uncompressed) in 21 square feet of floor space. Robotic performance of 600 cartridge exchanges per hour. Average access time to any file less than 30 sec. (including cartridge exchange, drive load and search to data). 1 to 4 tape drives per library. Ethernet NetSCSI protocol robotics control. Starting single unit price: $300K. (, 94/12/23)
Subject: [6.6.2] Odetics From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Odetics makes a thing called a DataTower that holds ~250 S-size D-2 cartridges. It used to be, but is no longer, sold through EMASS for use with the ER-90 (the Ampex/EMASS D-2 drive). It's a small silo that sits in front of one rack of drives. They also make an expandable library known as the DataLibrary, with a maximum capacity of ten petabytes(!) (ten million gigabytes). A robot handler runs on a track down an aisle lined with cartridges, and tape drives at one (both?) end(s) of the aisle. I think the aisles can vary in length, and they can be lined up next to each other and I believe cartridges will pass between them. (Note: since their acquisition of GRAU (above) EMASS no longer sells Odetics. I don't know if these are still available directly from Odetics and who you'd get to do the integration work. (rdv, from (Dave Barnes), 1996/3/22))
Subject: [6.7] ID-1 From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries)
Subject: [6.7.1] Sony DMS, PetaSite {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Sony sells three autochangers for their ID-1 line of tape drives, based on their broadcast line of autochangers. These are known as the DMS Series, models 24, 300M, and 700M. Not surprisingly, they hold, respectively, 24 (S,M, or L cassettes), 300 (M only) and 700 (M only) cassettes for capacities of 2.3, 13, and 30 terabytes. They have also announced something called PetaSite, which they claim expands to 3 petabytes and supports both ID-1 and DTF in a single system. (rdv, 1996/3/22)
Subject: [6.8] Optical Disk (MO,WORM) Libraries From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Several other Japanese manufacturers make optical libraries, I think, mostly in support of their own drives. (SHMO)
Subject: [6.8.1] Hitachi 448 GB optical library From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) 12-inch worm, up to 7GB per platter, 2-4 drives, additional cartridge expansion unit increases capacity 560 GB to 1,008 GB. Drive rates up to 2.22 MB/sec. Phone: 800/HITACHI
Subject: [6.8.2] HP MO Autochangers From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Makes several models, from 16 disks and one drive up to 144 disks and ?4? drives. These are very popular.
Subject: [6.8.3] Maxoptix MO Autochangers From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Makes several models in the MaxLyb series, the 52, 120 and 180, which correspond to the capacity in gigabytes for 1.3 GB drives. They hold, respectively, 2 (52), 2 or 4 (120) and 2, 4 or 6 (180) drives. They also have a fairly mysterious thing called the Axxis^26, a "high speed network file retrieval & backup server," which is obviously an MO autochanger, apparently bundled with a license for Palindrome Backup Director, suitable for attaching to your Netware file server? tel: (408)954-9700, (800)848-3092 fax: (408)954-9711 (rdv,95/02/14)
Subject: [6.8.4] MountainGate {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Now has the OSS-626, which holds 450-626 disks and 2-24 full-height HP drives. Also a new expandable multi-chassis autochanger similar to the D-360 DLT autochanger is available. See above under VHS for contact info.
Subject: [6.8.5] DISC DocuStore {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Makes large libraries (up to ~1,000 5.25" MO catridges, 2.6TB for standard MO or 4.6TB for non-standard); see (Stephen Fister <fister@Synopsys.COM>, 96/8/7)
Subject: [6.8.6] Kodak {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Kodak makes their own autochangers for their large (?12"?) optical drive.
Subject: [6.8.7] Sony {Brief} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Sony makes their own jukeboxes for their 12" WORMs and for 5.25" MO. is the place to start.
Subject: [6.9] CD-ROM Jukeboxes From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries)
Subject: [6.9.1] Pioneer From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) From: (Mike Caplinger) Subject: driver software for Pioneer DRM-5004X CDROM jukebox Date: Tue Aug 23 10:09:00 PDT 1994 Organization: UTexas Mail-to-News Gateway Lines: 13 Pioneer recently announced their DRM-5004X CDROM jukebox, which has four quad-speed drives and holds 500 CDs for under $20,000. Mike Caplinger Pioneer also has a 6-disk mini-changer, where SCSI LUNs 0-5 correspond to the individual disks; accessing one causes a mount. (Brian A Berg <>, 1996/3/29) There's also an 18-disk model. You can find info on all three at (rdv, 96/8/5)
Subject: [6.9.2] CyberTower {Brief, New} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) has frustratingly little info on a product that apparently is 7 CD-ROM drives made to behave like a single SCSI target. Not really an autochanger, more of an array. Not sure who the manufacturer is; the same unit is available from Procom (rdv,96/8/5)
Subject: [6.9.3] NSMJukebox {Brief, New} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) describes what they call "the universe's fastest CD-ROM jukebox". 150 platters (90GB), up to four drives. (rdv, 96/8/5)
Subject: [6.9.4] Nakamichi {Brief, New} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) A 4-disk changer built on into an 8x reader. (rdv,96/8/5)
Subject: [6.9.5] CDI Juke Box Library {Brief,New} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) A 28-disk changer (standalone network server?) with up to four drives, and a built-in PC w/ 128 MB RAM and a 1GB disk. Available from (rdv,96/8/5)
Subject: [6.9.6] K & S M-200 {Brief, New} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) A 200-disk autochanger. Available from (rdv,96/8/5)
Subject: [6.9.7] DISC {Brief, New} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) Makes large libraries (up to ~1,500 media slots and up to 32 drives); see (Stephen Fister <fister@Synopsys.COM>, 96/8/7)
Subject: [6.9.8] Meridian {Brief, New} From: Robotics (Autochangers, Jukeboxes, Stackers, Libraries) CD Net Universal Server from Meridian, Not really an autochanger, but an array of CD-ROM drives in a box with an NFS or Netware interface. (rdv, 97/6/30)
Subject: [7] File Systems From: File Systems This topic is also discussed frequently in comp.os.research. See
Subject: [7.1] NFS {Brief} From: File Systems The Network File System, originally developed by Sun Microsystems and now pretty standard in the Unix world, and clients exist for PC, Mac, VMS, and other non-Unix OSes. V2, the common version, supports single files only up to 2^32 (4GB) bytes. I'm not sure if there are any limits to a file system size under NFS, other than those imposed by the client and server OSes (SHMO). NFS is defined in RFC 1094. V3 is now RFC 1813. There is at least one newsgroup devoted specifically to NFS: comp.protocols.nfs.
Subject: [7.1.1] NFS V3 From: File Systems NFS V3 supports 64-bit files and write caching. The first implementation was from Digital with DEC OSF/1 V3.0 for Alpha AXP. Silicon Graphics supports it on IRIX 5.3. Cray will support it on UNICOS 9. I don't know about other vendors but I have heard rumours that the releases coming in the second half of 1995 will support it. Further information on NFS V3 can be found from (, 95/1/22) Solaris 2.5, available Nov. 95, is reported to have V3 support. Network Appliances have it as of 3.0, Sept. 95. ( (Guy Harris), 95/10/6)
Subject: [7.2] AFS {Brief} From: File Systems The Andrew File System (SHMO). Allows naming of files worldwide as if they were a locally-mounted FS (from cooperating clients, of course). There's an "alt" group for AFS - "alt.filesystems.afs". Available commercially from Transarc.
Subject: [7.3] DFS {Brief} From: File Systems Another remote file system protocol that supports large files. I don't know anything about it, or if any implementations really exist yet.
Subject: [7.4] Log based file systems From: File Systems Further Information: %z InProceedings %K hpdb:Rosenblum91 %s (Thu Oct 17 11:12:07 1991) %A Mendel Rosenblum %A John K. Ousterhout %y UCBCS. %T The design and implementation of a log-structured file system %C Proc. 13th SOSP. %c Asilomar, Pacific Grove, CA %p ACM. SIGOPS %D 13 Oct. 1991 %P 1 15 %x This paper presents a new technique for disk storage management %x called a log-structured file system. A log-structured file system %x writes all modifications to disk sequentially in a log-like %x structure, thereby speeding up both file writing and crash %x recovery. The log is the only structure on disk; it contains %x indexing information so that files can be read back from the log %x efficiently. In order to maintain large free areas on disk for %x fast writing, we divide the log into segments and use a segment %x cleaner to compress the live information from heavily fragmented %x segments. We present a series of simulations that demonstrate the %x efficiency of a simple cleaning policy based on cost and benefit. %x We have implemented a prototype log-structured file system called %x Sprite LFS; it outperforms current Unix file systems by an order of %x magnitude for small-file writes while matching or exceeding Unix %x performance for reads and large writes. Even when the overhead for %x cleaning is included, Sprite LFS can use 70% of the disk bandwidth %x for writing, whereas Unix file systems typically can use only %x 5--10%. ( Also, these papers: Ousterhout and Douglis, "Beating the I/O Bottleneck: A Case for Log- structured File Systems", Operating Systems Review, No. 1, Vol. 23, pp. 11-27, 1989, also available as Technical Report UCB/CSD 88/467. Rosenblum and Ousterhout, "The Design and Implementation of a Log- Structured File System", ACM SIGOPS Operating Systems Review, No. 5, Vol. 25, 1991. Seltzer, "File System Performance and Transaction Support", PhD Thesis, University of California, Berkeley, 1992, also available as Technical Report UCB/ERL M92. Seltzer, Bostic, McKusick and Staelin, "An Implementation of a Log- Structured File System for UNIX", Proc. of the Winter 1993 USENIX Conf., pp. 315-331, 1993. listed from the man page for mount_lfs under FreeBSD-2.1.5. (rdv, 97/1/17)
Subject: [7.5] Mainframe File Systems From: File Systems The WWW FAQ contains some information about mainframe file systems.
Subject: [7.6] Parallel System File Systems From: File Systems This discussion comes up occassionally on comp.arch and comp.os.research. I don't know which newsgroups/mailing lists the PIO (Parallel I/O) people hang out in, but it doesn't seem to be here. They show up occassionally in comp.sys.super and comp.parallel. They do have their own conferences, though. The important work seems to be going on with the supercomputing gang -- LLNL, CMU, Caltech, UIUC, Dartmouth, ORNL, SNL, etc. Work is also being done by the parallel database community, including vendors such as Teradata. A paper presented at the ACM International Supercomputing Conference in 1993 showed what to me seemed to be pretty appalling performance for reading data and distributing it to multiple processors on an Intel Delta supercomputer (sorry I don't have the reference in front of me). (rdv, 94/8/12) The paper is old, now, and the Intel guys say they have improved performance to up to 130 MB/sec. on the new Paragon using their Parallel File System (PFS). There is an excellent web site on parallel I/O at Dartmouth: There is also a mailing list housed at Dartmouth, The annual conference is I/O in Parallel and Distributed Systems (IOPADS); 1997's is co-located with Supercomputing '97 in San Jose, Nov. 17. Papers are due March 25, 1997. See
Subject: [7.7] Microsoft Windows NT {Brief} From: File Systems I seem to recall that NT supports 64-bit file systems for its own native file systems? Anybody know for sure (SHMO)? (rdv, 94/8/24) From *Inside the Windows NT(TM) File System*, by Helen Custer: "NTFS allocates clusters and uses 64 bits to number them, which results in a possible 2^64 clusters, each up to 4KB. Each file can be of virtually infinite size, that is, 2^64 bytes long." "Clusters" can be between 512 and 4K bytes. The Win32 API supports 64-bit file sizes, albeit in a cheesy fashion reminiscent of V6 UNIX - no 64-bit integral types used, just pairs of 32-bit integral types. ( (Guy Harris), 95/10/6)
Subject: [7.8] Large Unix File Systems From: File Systems There is now an industry group working on standardizing an API for files larger than 2 GB (the max size normally supported on most Unix systems). More info as I get it. The WWW-enabled can have a look at and see the various proposals on the table. Note that it is VERY easy to confuse whether an OS supports _files_ larger than 2 GB or _file systems_ larger than 2 GB. My table lists some of both (thanks to (Benjamin Z. Goldsteen), Ed Hamrick ( and Peter Poorman ( for much of this information). It is straightforward for systems with 64-bit integers to support 64-bit files; for systems with 32-bit integers it is more complex. On most 32-bit systems the offsets passed around inside the kernel (most importantly, at the VFS layer) the file offsets and sizes tend to be passed as 32-bit (signed) integers, meaning no files >2^31. On most systems, the argument to lseek is of type off_t, which (on SunOS and Linux, and plausibly on OSF/1 and others) is declared in a header file as "typedef long off_t;". For clients to really have access to large files, three pieces are required: local FS support, an appropriate network protocol, and server support for 64-bit FSes. For FTP access, I believe _literally_ inifinitely large files are possible, but I'm not sure(SHMO). For NFS access, NFS V2 supports only 2GB files. NFS V3, just becoming available now, supports full 64-bit files, I believe (anybody have a reference to the docs? RFC? SHMO). With the notable exception of Unitree (which does not use, depend on, or appear as, a local FS on the server), server support for 64-bit files is provided only when the server's own local FSes are 64-bit. Even for the systems that _do_ support large files, not all are programmer or user-transparent for supporting large files. UniCOS is, OSF/1 is, ConvexOS is not (there are two system calls, lseek and lseek64, with 32-bit and 64-bit file offsets, respectively, though the Fortran interface is transparent). This brings up the related issues. A complete large files implementation needs not only the system calls, but also the stdio library and the runtime libraries for the languages (Fortran, Cobol,...). Further, system utilities (sed, dd, etcetera) need to be capable of dealing with large files. (It has been pointed out that the GNU C compiler runs on most of these machines, so it is possible to use "long long" as a 64-bit int on them, but what matters for file systems is the system compiler.) Here's the start of a table on these. Really such a simple table can't do the problem justice, but it'll give you an idea. Keep in mind that many of these systems support many file system types; I've listed only the most interesting so far from this point of view. I'd like to flesh it out more completely, though. 1 GB = 2^30, 1 TB = 2^40, 1 PB = 2^50, 1 EB = 2^60 NYR = Not Yet Released OS/hardware 64-bit C max max NFS info datatype par- file V3 updated tition size sup size (bytes) UniCOS (Cray vector) int, long ? 8 EB? ? 8/94 ConvexOS long long 1 TB 1 TB N 9/94 Alpha AXP OSF/1 V3.0 AFS long 128 GB 16 TB 8/94 9/94 Paragon OSF/1 ? 8 EB* 8 EB N 2/95 UTS (Amdahl) ? ? 8 EB? ? 8/94 HP/UX 9 (HP 9xxx) ? 4 GB ? ? 8/94 Silicon Graphics IRIX 5.2 EFS long long 8 GB 2 GB N 9/94 IRIX 6.0 EFS long 8 GB 2 GB N 9/94 (NYR) IRIX 5.3 XFS ?long long? ? ?TB? Y 9/94 (NYR) AIX (IBM RS/6000) 4.1 JFS long long 64 GB 2 GB N 8/94 Solaris 2.x (Sun Sparc) long long 1 TB 2 GB (soon?) 9/94 BSD 4.4 long long ? 8 EB? ? 8/94 Linux long long 1 TB 2 GB ? 9/94 DG/UX 5.4 long long 2 TB 2 GB ? 9/94 Alliant Concentrix long long ?>2 GB ?>2 GB N 9/94 (dead) * The Paragon PFS (Parallel File System), as I understand it, parallelizes access to the files; each partition striped across is limited to 2GB, so really the max partition size is 2GB * # of disks that can be attached. A slightly more detailed description of certain implementations is available with the WWW version. In addition, the HPSS (see above) supports large files, as does Unitree (though the Unitree interface to them is limited).
Subject: [7.9] Non-Unix Large File Systems From: File Systems (info about non-Unix large FSes also welcome; SHMO) OpenVMS (any version) supports 2TB files (32-bit unsigned block number, 9-bit offset) through its RMS interface (still limited to 2GB through the C run-time library), but file systems are limited to ~7GB (as of Open AXP 1.5 and OpenVMS VAX 6.0 the max volume size has been bumped to 1 TB). (from a friend, rdv, 94/8/26, and Rod Widdowson, Filesystems group, OpenVMS engineering, Scotland).
Subject: [8] (Device) Interfaces From: (Device) Interfaces There is a new web site with lots of info at (rdv, 96/2/21) Looks like it's class notes, so no idea how long it will stay up. Don't forget to see
Subject: [8.1] SCSI {Full} From: (Device) Interfaces SCSI is the Small Computer System Interface. It is standardized by ANSI X3T9.2. It is mostly aimed at storage devices, with command sets defined for disks, tapes, and autochangers, but also includes communications devices, printers, and scanners. It's daisy-chained, with a maximum of eight devices (including the host computer) on a single narrow bus (there are non-standard schemes for 16 devices on a wide bus). Any device can be an initiator, so it's possible to use the bus for sharing devices between hosts, provided your software can manage it. See also the newsgroup comp.periphs.scsi, especially for "How do I hook up a Brand X diskdrive to my Atavachron 9000 PDA?" type questions. There is also an FTP site for some working documents for the SCSI-3 committees and other X3T10 documents. See or You'll find good info at and at
Subject: [8.1.1] Single ended vs differential From: (Device) Interfaces This distinction is at the eletrical signalling level. However, single-ended is limited to total bus lengths of 6.0 meters, while differential can go up to 25 meters (SCSI-II). Differential is generally more robust to noise and cross-talk, but the bus drivers are more expensive. In theory no difference in transfer speed or capabilities, but in practice the added noise margin could mean higher _reliable_ transfer rates on your system, especially if your bus is long. Most disk drives and most low-end products are available only with a single-ended interface. A few devices are available with either as a purchase option, and a few are switchable by the user. The cables and connectors are the same for both, though the pinouts are (naturally) somewhat different. Plugging a single-ended device into a running differential bus or vice-versa may result in damage to one or more devices. Most newer devices have fuses or protection circuits utilitizing the DIFFSENSE signal to prevent device damage. There are now recommended icons used to distinguish between the two: single-ended differential /\ //\ / \ // \ < -- << -- \ / \\ / \/ \\/ Converters do exist that will allow you to hook up single-ended devices to a differential bus and vice-versa. People who have used them say they work great, but in theory they shouldn't work :-). As I understand it, changing the signalling introduces delays in some of the control signals that means that some devices could miss certain signal transitions. The best advice is to borrow one and try it, and see if it works in your system. One company's name is Paralan, (619)560-7266.
Subject: [8.1.2] Asynchronous vs Synchronous Transfers From: (Device) Interfaces Asynchronous transfers mean that every single byte must be acknowledged before the next can be transfered. Synchronous means that the device sending data can drop a series of transfers onto the bus, toggling REQ or ACK (as appropriate), and then sit back and wait for the corresponding pulses to return from the other device. Async transfers, involving much more waiting, are correspondingly slower. 2-4 MB/sec are good values for async transfers. Sync transfer speeds are established during a negotiation between the initiator and target, but devices are not required to use the full speed they negotiate for. This speed represents the maximum burst rate your device will use. Common values are 5 and 10 MB/sec. In practice, virtually every modern device supports synchronous transfers, but some implementations are better than others.
Subject: [8.1.3] SCSI-I vs SCSI-II vs SCSI-III From: (Device) Interfaces SCSI (now commonly known as SCSI-I) was the original 1986 standard, X3.131-1986. It specified the electrical level and some of the mid-layer issues involving messages and packet structure, but (I believe, my memory's bad) didn't formalize the Common Command Set (CCS), that was done independently. It supported a maximum burst rate of 5 MB/sec. on an 8-bit bus. ADDITIONAL INFORMATION Consult the SCSI standards documents, and the manuals for the device you are working with for more information. The "SCSI 1" specification document is called SCSI Specification, ANSI X3T9.2/86-109. Also of interest is the Common Command Set specification document SCSI CCS Specification, ANSI X3T9.2/85-3 SCSI-II received final approval in early 1994, but has been a de facto standard for several years. The CCS was standardized for a variety of different types of peripherals. The max allowable transfer rate was raised to 10 MT/s (see below). A 16-bit bus (Wide SCSI) and 32-bit bus (double-wide SCSI) are specified (see below). SCSI-III is the latest effort, and involves more cleanly separating the functionality into layers; the command layer is defined independently from the physical layer. In addition to the traditional parallel cable, there are efforts going on to define physical layers for Fibre Channel and a more generic Serial SCSI. Thus, there will be no SCSI-IV; only the individual pieces will be updated as necessary.
Subject: [8.1.4] Fast-Wide SCSI From: (Device) Interfaces The max allowable transfer rate was raised to 10 MT/s (mega-transfers per second) in SCSI-2, referred to as Fast SCSI. Note that this is NOT required, devices running at ANY speed below that may claim to be SCSI-II compliant! Fast implies SCSI-II, not the other way around! Fast Narrow is thus 10 MB/sec. Both the initiator (computer) and target (peripheral) must support fast transfer for it to be of any use, but intermixing fast and slow devices on a bus presents no operational problems (only performance ones). A 16-bit bus (Wide SCSI) and 32-bit bus (double-wide SCSI) are specified in SCSI-2. The wide busses require the use of a second cable in SCSI-2. The first cable is 50 pins, known as the A cable; the 2nd is 68 pins, known as the B cable. I know of no one actually using 32-bit SCSI, but it would also run on an A/B cable pair. Slow (or Normal) Wide is thus 5 MT/s * 2 Bytes/T, 10 MB/sec. Fast Wide is 20 MB/sec. Fast Double Wide would be 40 MB/sec. In the SCSI-3 physical layer spec (SCSI-PH), a single 68-pin cable, known as the P cable, is allowable for 8 or 16-bit busses. This is the option most people who have implemented Wide SCSI have chosen for the cabling, even though their upper layer is generally SCSI-2. There is a small movement (heard here on the net occassionally) to promote an Ultra-SCSI high-speed bus, with a burst rate of something like 20 MT/sec on very short cables. At present it is unclear what will happen to this effort. There is also talk, in conjunction with a change to low-voltage differential signalling, to go to 40MT/sec.
Subject: [8.1.5] Shared Busses / Performance {Brief} From: (Device) Interfaces Also known as, "It's only a 500KB/sec. tape drive, why do I care if the burst rate is only 2 MB/sec.?" or gets good marks for "plays well with others". Most of this is relevant to all shared busses, not just SCSI. burst v. sustained performance, disconnect, command overhead, etc.
Subject: [8.1.6] Cabling/Hot Plugging {Brief} From: (Device) Interfaces Nominally not supported.
Subject: [8.1.7] Third Party Transfers/Separation of Control & Data Paths {Brief} From: (Device) Interfaces SCSI-2 has commands that support third-party copying of data; one initiator tells device A to copy to device B. I don't know of any devices actually using this. Separation of control & data paths is a popular topic these days; can somebody comment on whether or not SCSI-3 supports this? I don't think so. (SHMO)
Subject: [8.2] IDE {Brief} From: (Device) Interfaces PC use Does not support overlapped I/O.
Subject: [8.3] IPI {None} From: (Device) Interfaces
Subject: [8.4] HIPPI {Brief} From: (Device) Interfaces 32-bit transfers at 25 MT/sec., 100 MB/sec. High Performance Parallel Interface is a unidirectional channel, i.e. you have to have an OUT cable and and IN cable for bidirectional transfers (you could have just one, if it's a read-only device like a scanner or write-only like a frame buffer). HiPPI is not a shared bus, but its frames can be switched through a crossbar switch (Network Systems is the premiere vendor). HiPPI is used for supercomputer-to-supercomputer networking (TCP/IP, no less), for RAID arrays (from Maximum Strategy, IBM and others), tape drives (Sony ID-1 drive), frame buffers and increasingly workstations (SGI and IBM support HiPPI, and 3rd-party Sbus cards exist for Sun). Due partly to the high overhead of HiPPI connections, many devices have elected to separate the control path from the data path. A common control path in that case is ethernet. Good resources from the HiPPI Networking Forum on the web at
Subject: [8.4.1] HIPPI-6400 {Brief} From: (Device) Interfaces An effort aimed at reaching 6400 Mbps (800 Mbytes/sec.) around the end of 1996. From rev 0.15 of the HIPPI-6400-PH specification, dated March 4, 1996, ftp'ed from Looks like the copper interface will be a cable with 44 micro-coax conductors, 22 in each direction. That's 16 data, 4 control, clock, and frame. A micro-packet is 32 data bytes and 64 bits of control information. I guess this means they're planning on 400 Mbps on each data line. The fiber variant uses 12 multimode fibers (in each direction, I presume, though it doesn't seem to say that): 8 data + 2 control + frame + clock, so presumably 800 Mbps on each fiber. Cable lengths in both cases TBD.
Subject: [8.5] Ultranet {Brief} From: (Device) Interfaces Fiber to the host, a hub with a backplane running at a total rate of ~1Gbps.
Subject: [8.6] Ethernet {Brief} From: (Device) Interfaces Generally related to normal inter-host networking, but also used as a control path for some HiPPI devices. Ampex also uses NetSCSI over ethernet to control their autochangers. Also, obviously, used for connecting many servers to their clients. Standard today is 10 Mbps, 100 Mbps (fast ethernet) is becoming more common.
Subject: [8.7] FDDI {None} From: (Device) Interfaces
Subject: [8.8] Fibre Channel Standard (FCS) From: (Device) Interfaces Rich Taborek of Amdahl has created an excellent web page on Fibre Channel at [Has draft Fibre Channel documents] [Has FCSI Fibre Channel Profiles] (rdv, 95/5/18 from Louis Grantham <>) Fibre Channel runs over coax or optical fibre (single or multimode), and even twisted pair. Fibre Channel comes in two basic forms -- Aribtrated Loop and switched fabric, which aren't (yet) interoperable. The host interfaces are rapidly becoming cheaper, but the switches are still expensive. Fibre Channel standards define several functional levels, from the physical interface up to the mapping to upper level functionality, e.g. how to do SCSI commands over FC. FC provides several "classes" of service, including dedicated circuit and acknowledged and unacknowledged datagrams. Can also be used for IP. (rdv, 96/10/28)
Subject: [8.9] ESCONN/SBCON {Brief} From: (Device) Interfaces Enterprise Systems CONNect. IBM's new mainframe attach -- fiber, I believe. The standardized version of this is known as SBCON, and Rich Taborek has once again created an excellent web page at
Subject: [8.10] IEEE P1394 (Serial Bus) From: (Device) Interfaces Apple's new standard for connecting devices via a high-speed serial bus. Good info at Also some info FTPable at (I think that's where I got those papers.) (rdv, 95/5/15) After having been somewhat dormant for a while, standards activity on new versions of 1394 is heating up again. Faster versions are in the works, as is a protocol for doing disks across it. (rdv, 96/10/28)
Subject: [8.11] Serial Storage Architecture (SSA) From: (Device) Interfaces IBM's new offering in the serial device interface sweepstakes. Some docs and tentative working standards available on the SCSI ftp site: The SSA Industry Association has a web server at Disk drives from Conner and Micropolis, and Pathlight and Adaptec and expected to do host adapters.
Subject: [8.12] S2I: IEEE P1285 Scalable Storage Interface From: (Device) Interfaces Chaired by Martin Freeman, Philips Research, this is an effort to standardize attaching disk drives directly to a system bus, making the disk's buffers readable as regular memory to the CPU. Sort of the opposite of network-attached storage, this couples the storage device design more closely to the hardware and OS of the host system. See for more info. (rdv, 1995/12/22)
Subject: [8.13] Multibus, Unibus, Mainframe Channels, and other history {None} From: (Device) Interfaces
Subject: [9] Other From: Other
Subject: [9.1] Video vs Datagrade tapes {brief, 5/94} From: Other cost vs reliability Are datagrade really more reliable? Warrantee of drive Cleaning cycle of drive Headlife of drive
Subject: [9.2] Compression From: Other See the comp.compression FAQ, and don't believe everything a vendor tells you. 2x compression is the standard going rate for lossless compression of arbitrary data, though some vendors claim 2.5 or 3x. Your mileage will vary with your data type. Compressing tape drives are common, but for disks and other block devices I don't know of anything being done. The unpredictability of the compression ratio generally makes it inappropriate for devices that need fixed capacities and addresses. Online compression of files can be accomplished by hand using utilities such as gzip and Unix compress. Some systems support software compression of files in the file system software, and will transparently compress and decompress files as needed. Stacker for PCs is one example; for Unix-like systems this seems to be common research for object-oriented file systems (including the GNU Hurd), but I don't know of any production versions offhand (SHMO). Compression may make your data more vulnerable to errors. A single error early in a compressed stream of data can render the entire data stream unreadable.
Subject: [10] Benchmarking From: Benchmarking See the comp.benchmarks FAQ, and don't believe everything a vendor tells you. There's a good paper on a new I/O benchmarking technique that also covers the pitfalls of I/O benchmarking in the Nov. '94 ACM Transactions on Computer Systems -- "A New Approach to I/O Performance Evaluation -- Self-Scaling I/O Benchmarks, Predicted I/O Performance", Peter Chen and David Patterson. Bonnie, IOZONE, IOBENCH, nhfsstone, one of the SPECs (SFS), are all useful for measuring I/O performance. There is also a program called BENCHMARK available from -- apparently a standardized set of scripts to test remote access to mass storage systems. In particular, note that based on a discussion here recently (8/96), it appears that some magazines (who ought to know better) are using HDT BenchTest as a disk drive performance measure, with the I/O sizes set so small that the disk drive cache is covering them all, resulting in anomalously high data rates (especially write rates). is the start of a reasonable-looking benchmark for PC hard drives (posted by, 9/96) ==== SPEC SFS ==== SPEC's System-level File Server (SFS) workload measures NFS server performance. It uses one server and two or more "load generator" clients. SPEC-SFS is not free; it costs US$1,200 from the SPEC corporation. There's a FAQ about SPEC posted sometimes in comp.benchmarks.
Subject: [11] Mass Storage Conferences From: Mass Storage Conferences There are two main academic conferences devoted specifically to mass storage (in addition to, of course, the supercomputer and OS conferences, and interesting stuff in databases, optical conferences, Usenix, SOSP...). NASA Goddard Space Flight Center and the IEEE run two conferences, in an 18-month or so alternating pattern. You'll find my notes on the letest Goddard conference at The contact for the NASA Mass Storage Conference (Sept. 17-19, 1996): Jorge Scientific Corporation 7500 Greenway Center Drive Suite 1130 Greenbelt, MD USA 20770 tel(301)220-1701 fax(301)220-1704 or if that fails email or There is some info available on the web at Also, the latest IEEE was in September '95: * The 14th IEEE Mass Storage Symposium was September 11-14, 1995 at Monterey, CA. More info from Bernie O'Lear ( or Sam Coleman ( Also of interest, there are the conferences on Very Large Database Systems. I have a reference somewhere... Interesting material shows up in the SPIE conferences.
Subject: [11.0.1] THIC Tape Head Interface Committee {Brief, New} From: Mass Storage Conferences I would like to bring to your attention the THIC Home Page at the URL and its anonymous ftp archives at the URL THIC started out in the early 70's as the Tape Head Interface Committee under the auspices of the DoD, but has since grown and expanded to embrace most data recording technologies. THIC has been meeting four times a year, alternating between the east and west coasts. The last meeting was in Seattle WA on Jan 21 and 22, 1997, and the next will be on April 22 and 23 at the DoubleTree in Tysons Corner VA. The papers range from marketing, new product announcement and discussion, to the problems of the various recording technologies. Since October 1995, I have been trying to collect as many of the papers as I could from each of the meetings and have been placing them in Adobe PDF on the THIC archives at I also maintain a no-frills home page where the agenda is displayed, with links to papers which are available in the archives. (P.C. Hariharan, 97/2)
Subject: [12] MTBF (Mean Time Between Flareups, er, Failures) From: MTBF (Mean Time Between Flareups, er, Failures) There is a short FAQ-like document available from IBM at No math for the statistically inclined, but explains in clear prose what IBM at least means when they say MTBF. I will also note that, for a complex but reparable system such as an autochanger, each subsystem may have a separate MTBF and a different lifetime, which may be combined to give one figure for the unit as a whole. Here is a reasonably understandable, but somewhat long, description of MTBF. Thanks to Kevin Daly (president of Odetics, wrote in 10/95 for this FAQ. After some waffling, I've included the whole thing, despite its length. =============================================================== M T B F In order to understand MTBF (Mean Time Between Failures) it is best to start with something else -- something for which it is easier to develop an intuitive feel. This other concept is failure rate which is, not surprisingly, the average (mean) rate at which things fail. A "thing" could be a component, an assembly, or a whole system. Some things -- rocks, for example -- are accepted to have very low failure rates while others -- British sports cars, for example -- are (or should be) expected to have relatively high failure rates. It is generally accepted among reliability specialists (and you, therefore, must not question it) that a thing's failure rate isn't constant, but generally goes through three phases over a thing's lifetime. In the first phase the failure rate is relatively high, but decreases over time -- this is called the "infant mortality" phase (sensitive guys these reliability specialists). In the second phase the failure rate is low and essentially constant -- this is (imaginatively) called the "constant failure rate" phase. In the third phase the failure rate begins increasing again, often quite rapidly, -- this is called the "wearout" phase. The reliability specialists noticed that when plotted as a function of time the failure rate resembled a familiar bathroom appliance -- but they called it a "bathtub" curve anyway. The units of failure rate are failures per unit of "thing-time"; e.g. failures per machine-hour or failures per system-year. What, you may ask, does all this have to do with MTBF? MTBF is the inverse of the failure rate in the constant failure rate phase. Nothing more and nothing less. The units of MTBF are (or, should be) units of "thing-time" pre failure; e.g. machine-hours per failure or system-years per failure but the "thing" part and the "per failure" part are almost always omitted to enhance the mystique and confusion and to make MTBF appear to have the units of "time" which it doesn't. We will bow to the convention of speaking of MTBF in hours or years -- but we all know what we really mean. What does MTBF have to do with lifetime? Nothing at all! It is not at all unusual for things to have MTBF's which significantly exceed their lifetime as defined by wearout -- in fact, you know many such things. A "thirty-something" American (well within his constant failure rate phase) has a failure (death) rate of about 1.1 deaths per 1000 person-years and, therefore, has an MTBF of 900 years (of course its really 900 person-years per death). Even the best ones, however, wear out long before that. This example points out one other important characteristic of MTBF -- it is an ensemble characteristic which applies to populations (i.e. "lots") of things; not a sample characteristic which applies to one specific thing. In the good old days when failure rates were relatively high (and, therefore, MTBF relatively low) this characteristic of MTBF was a curiosity which created lively (?) debate at conventions of reliability specialists (them) but otherwise didn't unduly bother right-thinking people (us). Things, however, have changed. For many systems of interest today the required failure rates are so low that the MTBF substantially exceeds the lifetime (obviously nature had this right a long time ago). In these cases MTBF's are not only "not necessarily" sample characteristics, but are "necessarily not" sample characteristics. In the terms of the reliability cognoscenti, failure processes are not ergodic (i.e. you can't blithely trade population statistics for time statistics). The key implication of this essential characteristic of MTBF is that it can only be determined from populations and it should only be applied to populations. MTBF is, therefore an excellent characteristic for determining how many spare hard drives are needed to support 1000 PC's, but a poor characteristic for guiding you on when you should change your hard drive to avoid a crash. MTBF's are best determined from large populations. How large? From every point of view (theoretical, practical, statistical) but cost, the answer is "the larger, the better". There are, however, well established techniques for planning and conducting test programs to develop specified levels of confidence in a thing's MTBF. Establishing an MTBF at the 80% confidence level, for example, is clearly better, but much more difficult and expensive, than doing it at a 60% confidence level. As an example, a test designed to demonstrate a thing's MTBF at the 80% confidence level, requires a total thing-time of 160% of the MTBF if it can be conducted with no failures. You don't want to know how much thing-time is required to achieve reasonable confidence levels if any failures occur during the test. What, by the way, is "thing-time"? An important subtlety is that "thing-time" isn't "clock time" (unless, of course, your thing is a clock). The question of how to compute "thing-time" is a critical one in reliability engineering. For some things (e.g. living thing) time always counts but for others the passage of "thing-time" may be highly dependent upon the state of the thing. Various ad hoc time corrections (such as "power on hours" (POH)) have been used, primarily in the electronics area. There is significant evidence that, in the mechanical area "thing-time" is much more related to activity rate than it is to clock time. Measures such as "Mean Cycles Between Failures (MCBF)" are becoming accepted as more accurate ways to assess the "duty cycle effect". Well-founded, if heuristic, techniques have been developed for combining MCBF and MTBF effects for systems in which the average activity rate is known. MTBF need not, then be "Mysterious Time Between Failures" or "Misleading Time Between Failures", but an important system characteristic which can help to quantify the suitability of a system for a potential application. While rising demands on system integrity may make this characteristic seem "unnatural", remember you live in a country of 250 million 9- million-hour MTBF people! =================================================================== Kevin C. Daly President ATL Products (714) 774-6900
Subject: [13] Mass Storage Reports From: Mass Storage Reports There are a number of consultants who also write regularly updated in-depth reports (and sometimes post here) about various aspects of the mass storage market; if you're going to get into this business or are planning on spending many thousands or millions of dollars on equipment, talking to one of them might be a good idea. Sanjay Ranade ( is one of the ones who both writes and posts here (he also has a couple of reasonably-priced books about mass storage). Infotech's reports include HSM, network backup, magtape and libraries. Others include Disk/Trend (Mountain View, CA, 405-961-6209) (good info there) and Freeman Reports (805-963-3853). Strategic Research Corporation has numerous white papers and good links available at, including networked storage. Some of them seem biased in particular directions, so caveat emptor.
Subject: [14] Network-Attached Peripherals {Brief} From: Network-Attached Peripherals {Brief} Coming soon. My own research is in this area; if you're lucky you might find some pointers by going through my home page http:// Contributions welcome. Look for "A Brief Survey of Current Work on Network-Attached Peripherals" in the January '96 ACM Operating Systems Review, by yours truly. An expanded, updated version is available on the web at (rdv, 96/1/22) is Garth Gibson's Parallel Data Lab, where they're doing excellent work on network-attached storage devices. At Lawrence Livermore, they're doing a network-attached RAID array to integrate into HPSS; see The ViewStation work at MIT, is concentrating on ATM-attached peripherals, using ATM as a system-area network. The Netstation project (which I work on at ISI) is focusing on IP-connectible peripherals, using a gigabit network as the system backplane.
Subject: [15] Other References From: Other References
Subject: [15.1] Print From: Other References Computer Technology Review magazine, 310/208-1335, free to some. Electronic News, weekly, 800/722-2346. MacWeek, June 7, 1993, Page 36+ IEEE Computer had a full issue in March 94 on I/O subsystems There are also two books by Sanjay Ranade (, who posts here occassionally. One is _Mass Storage Technologies_ (1991ish?), the other, newer one is _Mass Storage Systems_. I've read the first one, it's a little short on detail but a good overview.
Subject: [15.2] Web From: Other References standards and tons of info. performance reports, media surveys, etc. Goes into a lot of detail on topics such as archival stability. lists some resellers and manufacturers of storage. has good information about PC hardware, including old interfaces, floppies, controllers, etc. It has a LONG list of specs for hard drives. also has good info on hard drives and CD-ROM drives. lists storage products and market projections.
Subject: [15.3] Newsgroups From: Other References You're in the primary one ( You'll also find info in the groups on SCSI, PC hardware, and specific operating systems. I'll try to add pointers to their FAQs soon. The FAQ for can be found at
Subject: [15.4] Research Papers From: Other References I'm collecting reviews and a list of papers now, I expect to add it in a few weeks. Contributions/suggestions welcome.
Subject: [16] ORIGINAL CALL FOR VOTES From: ORIGINAL CALL FOR VOTES NAME: STATUS: unmoderated DESCRIPTION: storage system issues, both software and hardware CHARTER: To facilitate and encourage communication among people interested in computer storage systems. The scope of the discussions would include issues relevant to all types of computer storage systems, both hardware and software. The general emphasis here is on open storage systems as opposed to platform specific products or proprietary hardware from a particular vendor. Such vendor specific discussions might belong in or comp.periphs. Many of these questions are at the research, architectural, and design levels today, but as more general storage system products enter the market, discussions may expand into "how to use" type questions. RATIONALE: As processors become faster and faster, a major bottleneck in computing becomes access to storage services: the hardware - disk, tape, optical, solid-state disk, robots, etc., and the software - uniform and convenient access to storage hardware. A far too true comment is that "A supercomputer is a machine that converts a compute-bound problem into an I/O-bound problem." As supercomputer performance reaches desktops, we all experience the problems of: o hot processor chips strapped onto anemic I/O architectures o incompatable storage systems that require expensive systems integration gurus to integrate and maintain o databases that are intimately bound into the quirks of an operating system for performance o applications that are unable to obtain guarantees on when their data and/or metadata is on stable storage o cheap tape libraries and robots that are under-utilized because software for migration and caching to disk is not readily available o nightmares in writing portable applications that attempt to access tape volumes This group will be a forum for discussions on storage topics including the following: >1. commercial products - OSF Distributed File System (DFS) based on Andrew, Epoch Infinite Storage Manager and Renaissance, Auspex NS5000 NFS server, Legato PrestoServer, AT&T Veritas, OSF Logical Volume Manager, DISCOS UniTree, etc. >2. storage strategies from major vendors - IBM System Managed Storage, HP Distributed Information Storage Architecture and StoragePlus, DEC Digital Storage Architecture (DSA), Distributed Heterogeneous Storage Management (DHSM), Hierarchical Storage Controllers, and Mass Storage Control Protocol (MSCP) >3. IEEE 1244 Storage Systems Standards Working Group >4. ANSI X3B11.1 and Rock Ridge WORM file system standards groups >5. emerging standard high-speed (100 MB/sec and up) interconnects to storage systems: HIPPI, Fiber Channel Standard, etc. >6. POSIX supercomputing and batch committees' work on storage volumes and tape mounts >7. magnetic tape semantics ("Unix tape support is an oxymoron.") >8. physical volume management - volume naming, mount semantics, enterprise-wide tracking of cartridges, etc. >9. models for tape robots and optical jukeboxes - SCSI-2, etc. >10. designs for direct network-attached storage (storage as black box) >11. backup and archiving strategies >12. raw storage services (i.e., raw byte strings) vs. management of structured data types (e.g. directories, database records,...) >13. storage services for efficient database support >14. storage server interfaces, e.g., OSF/1 Logical Volume Manager >15. object server and browser technology, e.g. Berkeley's Sequoia 2000 >16. separation of control and data paths for high performance by removing the control processor from the data path; this eliminates the requirements for expensive I/O capable (i.e., mainframe) control processors >17. operating system-independent file system design >18. SCSI-3 proposal for a flat file system built into the disk drive >19. client applications which bypass/ignore file systems: virtual memory, databases, mail, hypertext, etc. >20. layered access to storage services - How low level do we want device control? How to support sophisticated, high performance applications that need to bypass the file abstraction? >21. migration and caching of storage objects in a distributed hierarchy of media types >22. management of replicated storage objects (differences/similarities to migration?) >23. optimization of placement of storage objects vs. location transparency and independence >24. granularity of replication - file system, file, segment, record, etc., >25. storage systems management - What information does an administrator need to manage a large, distributed storage system? >26. security issues - Who do you trust when your storage is directly networked? >27. RAID array architectures, including RADD (Redundant Arrays of Distributed Disks) and Berkeley RAID-II HIPPI systems >28. architectures and problems for tape arrays - striped tape systems >29. stable storage algorithm of Lampson and Sturgis for critical metadata >30. How can cheap MIPS and RAM help storage? - HP DataMesh, write-only disk caches, non-volatile caches, etc. >31. support for multi-media or integrated digital continuous media (audio, video, other realtime data streams) This group will serve as a forum for the discussion of issues which do not easily fit into the more tightly focused discussions in various existing newsgroups. The issues are much broader than Unix (comp.1.*, comp.os.*), as they transcend operating systems in general. Distributed computer systems of the future will offer standard network storage services; what operating system(s) they use (if any) will be irrelevant to their clients. The peripheral groups (comp.periphs, comp.periphs.scsi) are too hardware oriented for these topics. Several of these topics involve active standards groups but several storage system issues are research topics in distributed systems. In general, the standards newsgroups ( are too narrowly focused for these discussions.

Subject: [17] Original Author's Disclaimer and Affiliation: From: Original Author's Disclaimer and Affiliation: This information is believed to be reasonably accurate although I do not verify every submission. Neither the United Stages Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefullness of any informatin, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendatin, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. --- Joseph Stith,, 708/840-3846 Assistant to the Computing Division Head -- IRM Planning Computing Division, Fermilab, PO Box 500, MS 120, Batavia, IL 60510
Subject: [18] Copyright Notice From: Copyright Notice This compilation of material is copyright Rod Van Meter, Permission is granted to copy this material, provided this copyright notice is retained. The contents are not to be significantly modified without the express written consent of the author. This is just to keep the various authors of this material from being substantially misquoted or abused, not to restrict use of the information. Permission to include this FAQ in published compilations (CD-ROM or book) will be granted upon direct request.
Subject: [19] Additional Topics to be added From: Additional Topics to be added File Systems: Unix, IBM, VMS, Tops-20, Extent-based, Amiga, Mac (resource & data forks) FTP Sites Volume Sets & Partitions Important People/Mass Storage History Books & Other Publications Principles for Evaluating New Technologies Performance Evaluation cacheing seek time measurement concurrent operations queueing theory Head Lifetime Versioning in File Systems Managing Risk Media Migration/Managing Change Physical v. Logical Addressing (seek optimizations, etc.) Channels v. Busses Intelligent Storage Subsystems DEC's HSC-50 and star cluster for VAXen Mainframe & Supercomputer I/O controllers Security The broadcast and home audio/video / mass storage connection Databases and Mass Storage File System Research: watchdogs, named pipes, compressing FSes The naming problem: Prospero Distributed Locking & Update Content-Addressable Storage & Other Unusual Ideas The old film-storage system Sam Coleman talks about Byte Ordering Supercomputer Storage Companies: Adstor, Avastor I/O Benchmarks User file systems System CPU & bus loads for file system work Memory-Mapped Files Persistent Object Systems & their files The VFS layer in Unix What to look for in a backup product Offsite Storage v. Network Backup Test Equipment -- SCSI & HiPPI Analyzers (reorganize along small user/large user/developer lines?) (need to date every entry if possible) terminology

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