Digital Equipment StorageWorks UltraSCSI DS-BA370 Series, User Manual

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Single-Ended I/O Modules
UltraSCSI RAID Enclosure 5–3
Replacing I/O Modules and Cables
Replacing an I/O module or a cable without first shutting down the
controller can adversely affect data integrity. Removal of the I/O module
causes the EMU to report the following error conditions to the controller:
(1) Installation of different I/O modules. (2) Loss of TERMPOWER.
Either of these error conditions can cause the controller to cease operating
without implementing procedures to protect the data.
Before you remove an I/O module or an expansion cable, completion of the
of the following procedures is mandatory (1) Shut down the array
controller, and (2) Turn off the enclosure power. Failure to do so can
induce a controller error condition.
Expanding the UltraSCSI Bus
Each I/O module has a UltraSCSI single-ended bus expansion integrated
circuit that isolates the internal and external SCSI bus, enhances SCSI
signals, and extends the length of the UltraSCSI bus.
The two, 68-pin, VHDCI receptacle connectors are the connection points
for expanding the SCSI buses between enclosures. These connectors are
wired in parallel and can act as a trilink connector. In an expansion
configuration, DIGITAL recommends a maximum cable length of
2 m (6.3 ft) between enclosures.
_____________________ Note ______________________
Connecting a cable to the right I/O module connector removes
the external SCSI bus termination from the module.
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