Compaq StorageWorks UltraSCSI RAID Enclosure (DS-BA370 Series) User's Guide (EK-BA370-UG. C02, September 1998)

Single-Ended I/O Module
UltraSCSI RAID Enclosure 5–3
I/O Module and Expansion Cable Error Conditions
Removal of an I/O module causes the EMU to report the following
error conditions to the controller:
• Installation of different I/O modules
• Loss of TERMPOWER
Either of these error conditions might cause the controller to cease
operation without implementing procedures to protect the data.
Before removing an I/O module or an expansion cable, completion of
the following procedures is mandatory to prevent inducing a
controller error condition:
1. Clear the cache and shut down the array controller.
2. Turn O
FF the enclosure power.
Caution
Replacing an I/O module or an expansion cable without
first shutting down the controller can adversely affect data
integrity.
Expanding the UltraSCSI Bus
Each I/O module has an UltraSCSI single-ended bus expansion
integrated circuit that isolates the internal and external SCSI bus,
enhances SCSI signals, and allows the use of a longer UltraSCSI bus
cable.
Two 68-pin VHDCI receptacle connectors on the I/O module are the
connection points for expanding the SCSI buses between enclosures.
These connectors are wired in parallel and act as a
trilink connector
.
In an expansion configuration, Compaq recommends a maximum
cable length of 2 m (6.6 ft) between enclosures.