Spectra Logic 10000 manual The SCSI Bus, Single-Ended, LVD, or HVD, Fast/Slow and Wide/Narrow SCSI

Appendix A. Library Specifications

The SCSI Bus

When considering SCSI bus configuration, be sure to note:

•Whether the bus and attached devices are single-ended, low-voltage differential (LVD) or high-voltage differential (HVD)

•Whether the bus and attached devices are fast/slow or wide/narrow

Single-Ended, LVD, or HVD

All SCSI devices attached to a bus must be of the same type, either single-ended, LVD or HVD; this includes the drives, the adapter card and the terminators. Single-ended devices use one line to transmit bus signals between devices. Differential devices use two lines to transmit bus signals between devices.

•A single-ended SCSI bus has a maximum length of 1.5 feet with fast/wide device.

•An LVD SCSI bus has a maximum length of 39.4 feet.

•An HVD SCSI bus has a maximum length of 82 feet.

Fast/Slow and Wide/Narrow SCSI

Fast/slow and wide/narrow refer to the signal configuration for different kinds of SCSI busses. The Spectra 10000 library uses the SCSI fast/wide standard.

•Slow SCSI means that the bus used allows transfer speeds of 5 MB/sec to 10 MB/sec, depending on bus width.

•Ultra-2 SCSI and Wide Ultra-2 SCSI allow transfer speeds of 40 MB/sec to 80 MB/sec.

•Fast SCSI means that the bus used allows transfer speeds of 10 MB/sec to 20 MB/sec, depending on bus width.

•Narrow SCSI means that the bus used is 8 bits wide.

•Wide SCSI means that the bus used is 16 bits wide.

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