Datacom Systems J Class 1. , Determining SCSI Bus Length

C-9
Fast, Wide SCSI-3 Bus Configuration Constraints
Fast, wide SCSI-3 does not work with the single-ended standard
SCSI-2. Table C–4 shows the configuration constraints for each fast,
wide SCSI-3 device type.
Table C–4. Fast, Wide SCSI-3 Bus Configuration Constraints
External Fast, Wide SCSI-3 Devices
SCSI-3 Drive (fast, wide disk drives only) 15
SCSI-3 Disk Arrays (addressed as single drive) 7
Maximum Number of Each
Type of Device Allowed
CAUTION: Do not mix single-ended and fast, wide SCSI
peripherals together on the same bus.
This section helps you to determine the total length of the single-en-
ded standard SCSI-2 bus and the fast, wide SCSI-3 bus.
Single-Ended SCSI-2 Bus Length
Follow these instructions to calculate your total single-ended standard
SCSI-2 bus length (including the system unit, external SCSI-2 de-
vices, and SCSI-2 interconnect cables) using Table C–5:
1. Find all of your external SCSI-2 devices in the first column. In
the third column, write the SCSI-2 bus lengths (from the second
column) that correspond to your devices.
NOTICE: In the third column, the length for the System
Unit is already listed. This number must always
be used for the system unit.
Determining
SCSI Bus
Length