User`s guide

1-4 TL891 MiniLibrary System User's Guide
Compaq Confidential – Need to Know Required
Writer: Everett Godaire Project: TL891 MiniLibrary System User's Guide Comments:
Part Number: ER-TL891-UA.A01 File Name: b-ch1 Introduction Last Saved On: 3/1/99 4:07 PM
SCSI Interface Configurations
Systems are equipped with TZ89 drives use a Fast/Wide SCSI interface using
high-density 68-pin D-series connectors. The section on SCSI Interfaces in
Chapter 3, Installation, describes the available interface options.
SCSI Bus Performance Considerations
Data Transfer Rate
The data transfer rate of the MiniLibrary is dependent on the type and number
of drives and on the SCSI bus configuration. The bandwidth of the SCSI bus is
limited. As a result, the transfer rate of exceptionally fast drives such as the
TZ89 can be limited by sharing a SCSI bus with another disc drive on tape.
Drives
With a standard SCSI interface, modules equipped with TZ89 drives have a
native data transfer rate of 5.0 MB/second, 10 MB/sec for two drives. The
rates for compressed data are dependent on compression ratio, record size,
data type, and other system parameters, but averages approximately 1:7.
Internal Cabling Configuration
The MiniLibrary System is wired in an independent-bus SCSI configuration.
That is, the robotics and each of the drives has its own SCSI bus. SCSI
jumpers are available for those applications requiring that some combination
of drives and robotics be daisy-chained to a single SCSI bus. These
configurations are described in more detail in the section on SCSI Interfaces in
Chapter 3, Installation.