Scsi Configuration; Scsi Bus Performance Considerations; Drives; Data Transfer Rate - Compaq StorageWorks SSL2000 Series Reference Manual

SCSI Configuration

The Library standard SCSI interface is a Fast/Wide LVD/SE using
high-density, 68-pin D-series connectors. For more information, see Chapter 2,
"Installation."

SCSI Bus Performance Considerations

Drives

With a standard Fast/Wide SCSI interface, each drive offers a sustained native
data transfer rate of 6 MB/s. In a two-drive unit, the total native rate is twice
these rates. The rates for compressed data are the native rates multiplied by the
compression factor, which depends on file content, but averages
approximately 2:1.

Data Transfer Rate

The data transfer rate of the Library depends on the type of the AIT drive,
number of drives, and the number of drives connected to the SCSI bus. The
library robotics imposes minimal loading on the bus.
AIT-2
AIT-2
Each drive has a maximum sustained rate of 12 MB/s with compressed data.
As a result, the transfer rate of a two-drive unit occupies the full bandwidth of
the bus. Sharing a SCSI bus among more than two drives degrades the
maximum performance of the library system.

Internal Cabling Configuration

Each SCSI bus in the Library is wired separately. The library robotics and
drive 1 share one bus; add-on drives are connected to separate SCSI buses.
SCSI jumper cables are available to allow the drives and robotics of a unit to
be daisy-chained to a single SCSI bus. For more detailed information, see
Chapter 2, "Installation."
Fast/Wide
Sustained
System Description 1-5
@ 40 MB/s (burst)
@ 6 MB/s (native)
@ 12 MB/s (compressed)