Operating instructions

4.12 External SCSI Expansion
There are two ways to connect external SCSI devices, such as tabletop
or rackmount storage: (a) PCI-based SCSI adapters and (b) the embed-
ded SCSI controller that is accessed through its external bulkhead
connector
. See Figure 4-24.
SCSI Expansion Rules
Observe the following rules to determine if a particular device can be used:
• The device must be supported by the operating system. Consult the sup-
ported options list.
• Do not exceed the maximum number of devices supported on the SCSI con-
troller to be used.
• Each device on the bus must have a unique SCSI ID.
• The entire SCSI bus length, from terminator to terminator, must not exceed
the following limits:
Fast differential SCSI or Ultra SCSI HVD 25 meters
Fast single-ended SCSI 3 meters
Ultra-wide SCSI 1.5 meters
Ultra 2 SCSI LVD 12 meters
Ultra 3 SCSI 12 meters
• Ensure that the SCSI bus is properly terminated and that no devices in the
middle of the bus are terminated.
• For best performance, wide devices should be operated in wide SCSI mode.
Configuring and Installing Components 4-35