Sizing the Task279
SCSI drives are the main limitations in using this type of device. They are however, cheaper and
somewhat easier to install than SCSI drives.
SCSI devices may also be used for mass storage, CD-ROM and DVD drives, but SCSI
devices can also include scanners, printers and other devices as well.
Up to seven devices may be attached to a single SCSI interface card inside the computer
and a computer may have more than one interface card. The total number of SCSI devices
installed on one computer is limited to the number of available interface slots on the mother-
board, times seven. On most modern workstations and servers this will allow a total number of
SCSI devices ranging from seven to over thirty. New SCSI standards allow more devices to be
connected to a single SCSI adapter.
SCSI drives are often configured in a Redundant Array of Inexpensive Disks (RAID) that
can be used to increase the reliability or the speed of the system. The trade-off in this configura-
tion is a loss of available drive space. The decrease in available space may be anywhere from
negligible to 50% of the total space on the drives depending on the RAID level used.
A.4Sizing the Task
When developing requirements for any computer system, it is important to understand exactly
what the system will be used for and how it will be used. Once the purpose of the computer is
understood, potential bottlenecks can be located and the potential for these to cause problems
can be minimized or eliminated.
A.5Stand Alone Development Workstation
In this configuration a workstation will be used to develop applications locally. The source code
will be kept on the local hard drive and the editing and compiling will take place on the same
machine.
The main concern with this configuration would be in the area of processor and memory,
and in having a backup system in place to ensure that data is not lost in the even of a hardware
failure.
A typical developer’s machine will have a processor in the 800+ MHz range and, depend-
ing on the scope of the application being developed, may have more than one processor. The
available memory will again depend on the type of application be written with typical machines
having in excess of 256 MB of memory and, in the event that large amounts of data have to be
manipulated, more than a gigabyte of memory.
The Linux OS, with development tools, can be installed utilizing approximately 1
gigabyte (GB) of disk space. The source code for the OS, which represents a decade of work
from people all over the globe, can be installed in less than 50 megabytes of space. A single
developer working full-time would have to be very productive in order to fill up most drives
available today as these typically come in 60GB sizes. Hard drive space is more often used for
development libraries and tools, separate runtime environments, etc.