Hardware prerequisites

Processor

x86 compatible (for example, Intel, AMD, or Cyrix). I've successfully installed DB2 Version 7.1 on a Pentium Pro 200 and a Pentium II 350. Your experiences with other x86 processors would be appreciated.

Memory

For application development, I've found 96 MB of RAM is enough to run a small database and test out your applications. Even the Control Center responds acceptably if your processor speed is fast enough. In my case, I was working with a Thinkpad 600 equipped with a Pentium 233 MMX processor and 96 MB of RAM. However, more memory is recommended if you're putting your database into production or running multiple services.

Free disk space

Of course, this depends on the components you install, but for a typical installation of the DB2 Version 7.1 server, the Administration Client, the Application Development Client, the documentation, and the creation of a sample database, you will need about 350 MB of free disk space.

Software prerequisites

glibc

2.1.2 or greater. This can be a tough part of Linux to upgrade on its own, so if your current distribution doesn't meet this requirement, I would strongly suggest upgrading your entire distribution. For example, I tried upgrading only the glibc portion of TurboLinux 4.0 from 2.1.1 to 2.1.3 and ran into a whole world of trouble.

DB2 Version 7.1 should work with glibc 2.1.1. IBM sets prerequisites based on the systems with which they tested.

kernel

2.2.12 or greater. I've upgraded to both 2.2.19 and 2.4.3 and recompiled the kernel for my own purposes, and DB2 seems to work as well as before.

DB2 Version 7.1 should work with a minimum of kernel 2.2.10. IBM sets prerequisites based on the systems with which they tested.

libncurses

4.x. For db2setup to work correctly, this version of the library must be available on your system with the following pathname: /usr/lib/libncurses.so.4.

libstdc++-libc6.1-1.so.2

A file or symbolic link by this exact name is mandatory. On most distributions, this is a symbolic link to libstdc++-2.9.0.so, but on several recent distributions this is a symbolic link to libstdc++-2.10.0.so.

In previous versions of this HOWTO, I stated that the exact version of libstdc++-2.9.0.so was mandatory. I was wrong.

pdksh

5.2 or greater. This is a public domain version of the Korn shell that both the DB2 installer and the DB2 commands require. You cannot do anything with DB2 without installing pdksh.

rpm

3.0 or greater. DB2 for Linux is distributed as a number of RPM packages, so you won't get far without this piece of software. For information on installing DB2 on distributions without using RPM, see Section 5.

Java

The IBM Developer Kit for Java, 1.1.8 or 1.3, is an optional component, but is required to:

• use the DB2 Control Center to administer your databases using a graphical user interface

• create or run Java applications, including stored procedures and user-defined functions

As of this writing, the minimum required level of the IBM Developer Kit for Java 1.1.8 is the March 22, 2000 release. You can get the IBM Developer Kit and Runtime Environment for Linux, Java Technology Edition, from the IBM Java Developer Kit downloads web site as follows:

• Version 1.1.8

• Version 1.3

Please note: Other versions of Java, such as the Blackdown or Sun JDKs, have not been tested with DB2 and are not supported by IBM. And no, none of the distributions I have seen so far package the IBM JDK. But do yourself a favour, and get the IBM Developer Kit for Java.

Web browser

DB2 calls the netscape command when you:

• display the online help for the DB2 Control Center

• display information using the DB2 Information Center

The easiest approach is to install Netscape Navigator or Communicator on your system. Netscape version 4.72 or above is required to display the Business Intelligence Quick Tour, because of its extreme use of JavaScript.

To use a browser other than Netscape to display online help or information, create a link called netscape to your preferred browser executable. The link must appear in your PATH. For example, to display online help with mozilla, you could create a link in /usr/local/bin with the following command:

bash# ln -s /usr/bin/mozilla-bin /usr/local/bin/netscape

Description of DB2 components

Administration Client

The Administration Client enables database administrators to administer local or remote DB2 servers from the command line. This component, without Java support or the Control Center, requires about 20 MB of disk space.

Control Center

The Control Center (db2cc) is an optional part of many DB2 components. It gives database administrators a graphical interface for administering local or remote DB2 servers. The Control Center includes the DB2 Information Center (db2ic), which gives you a graphical interface that provides a tree view of the DB2 documentation installed on your workstation organized by task or by title.

Note that both the Control Center and Information Center are Java applications, so their performance depends on your system's processor speed and available memory. This component requires about 90 MB of disk space.

You probably want to install the Control Center.

DB2 UDB Enterprise Edition, DB2 UDB Workgroup Edition, DB2 Personal Edition

These components determine the state of your DB2 installation as a database server. The core capabilities of the components are the same. The difference between Enterprise Edition and Workgroup Edition primarily has to do with how they are licensed--Enterprise Edition is licensed on a per-processor basis with unlimited users, while Workgroup Edition is licensed on a per-user basis. Enterprise Edition also gives you the capability to enable DB2 clients to connect to mainframe databases, like DB2 for OS/390 or DB2 for OS/400. In contrast, Personal Edition is a single user database server that is useful only for developing DB2 applications. You cannot use Personal Edition as a server because Personal Edition does not accept incoming remote connections.

Adding one of these components requires about 40 MB of disk space.

Options for DB2 servers

Replication

This option enables your DB2 server to replicate data to other DB2 servers, and, with additional software, across non-DB2 servers as well. This option requires about 5 MB of disk space.

Distributed Join for DB2 Data Sources

This option enables your DB2 server to participate in a join with data from other database servers. This option requires about 2 MB of disk space.

Application Development Client

The Application Development Client component installs the headers and libraries that you need to create applications using embedded SQL for C and C++, Call Level Interface (CLI), Java Database Connectivity (JDBC), or embedded SQL for Java (SQLJ). You also have the option of installing the source code for sample applications that demonstrate much of the functionality of DB2.

If you plan on developing applications for DB2, install the sample applications. The sample directories in /usr/IBMdb2/V7.1/samples/ contain build scripts (bld***) that include the compile and link options suitable for your own applications.

If you are trying to develop applications and you get an error like "That command is not supported in this environment" while trying to precompile a file, it's because you either did not install the Application Development Client, or you installed it after you created an instance and you have not used the db2iupdt command to update the instance. See Section 9.1 for more information on db2iupdt.

Including the sample applications, this component requires about 10 MB of disk space.

DB2 Product Library (HTML documentation)

Documentation is installed into the /usr/IBMdb2/V7.1/doc/ directory. For each language that you install, the DB2 installer creates a subdirectory with a five-character name corresponding to the language locale. Issue the db2help command to fire up your Web browser with a page that links to the documentation installed with DB2.

The English HTML (En_US) documentation requires about 90 MB of disk space.

_SHM_ID_BITS

This variable, defined in /usr/src/linux/include/asm/shmparam.h, determines the number of shared memory segment identifiers available to Linux. The default value for _SHM_ID_BITS in the kernel source is 7, which allows for a total of 2^7, or 128, shared memory segment identifiers.

On a single-processor machine, DB2 itself uses a set number (~15) of shared memory segment identifiers. On a machine with multiple processors, DB2 also requires one shared memory segment identifier per agent to take advantage of the Fast Communication Manager (FCM) feature of DB2. Because each DB2 connection requires one agent per processor, on a quad-processor machine the default value of _SHM_ID_BITS allows less than 32 simultaneous connections to a DB2 instance.

If you recompile the kernel yourself, you should be able to safely increase this value to 9.

MSGMNI

This variable determines the maximum number of message queue identifiers. For DB2 Version 7.1 to function correctly, the minimum value is 128, but for heavier use consider setting this value to 1024 or higher.

In the 2.2 kernel source, this variable is defined in /usr/src/linux/include/linux/msg.h. The default value of 128 is acceptable for small-scale use of DB2 Version 7.1.

In the 2.4 kernel source, this variable is defined in /proc/sys/kernel/msgmni. The default value of 16 must be increased to enable DB2 Version 7.1 to function correctly. The good news is that you can change this value without recompiling the kernel or rebooting your machine. For more information, see Section 12.

NR_TASKS

This variable, defined in /usr/src/linux/include/linux/tasks.h, determines the number of simultaneous processes that Linux supports. A second variable, MAX_TASKS_PER_USER, is defined as NR_TASKS/2. Since DB2 instances are treated as users by Linux, and each connection uses a single process, the maximum number of connections per instance is capped at the value of NR_TASKS/2.

The default value for NR_TASKS in the kernel source is 512, allowing a maximum of 256 simultaneous connections to a single DB2 instance. DB2 itself requires a few connections for overhead processes. If you recompile the kernel yourself, you should increase this value to something like 2048. The stock kernels shipped with the Red Hat, SuSE, and TurboLinux distributions increase the value of NR_TASKS to 2560 or above. However, Caldera OpenLinux eDesktop 2.4 ships with a kernel in which NR_TASKS is set to the default value of 512. Caldera users should increase the value of this variable and recompile the kernel.

SEMMNI

This variable, defined in /usr/src/linux/include/linux/sem.h, determines the number of semaphore identifiers that Linux supports. This variable is particularly important on symmetric multi-processing (SMP) machines. A unique semaphor identifier is required for each processor per agent (or connection); therefore, on a quad-processor machine, four semaphore identifiers are required per connection.

The default value for SEMMNI in the kernel source is 128, which, on a quad-processor machine, will only allow 32 simultaneous connections to a DB2 instance. If you recompile the kernel yourself, increase this value to something like 1024.