Digital Equipment StorageWorks UltraSCSI DS-BA370 Series, User Manual

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Introducing the UltraSCSI RAID Enclosure
Ultra SCSI RAID Enclosure 1–9
Expansion EMU
An environmental monitoring unit installed in an expansion enclosure is an
Expansion EMU. This EMU communicates with the master EMU over the
EMU—EMU communications bus. Upon loss of communications with the
master EMU, the expansion EMU assumes control of certain expansion
enclosure functions. In this state, the expansion EMU cannot communicate
with the UltraSCSI controller
I/O Module
This device provides termination for the internal UltraSCSI buses and is the
connection point for the cables connecting the six buses to an expansion
enclosure.
SCSI Bus Controllers
A hardware–software device that manages SCSI bus communications to
devices. Controllers typically differ by the type of interface to the host and
provide functions beyond those the devices support. Other terms commonly
used include array controller or controller..
Cache Module
A storage buffer required for each bus controller.
ECBs
ECBs (external cache batteries) provide backup power to the cache module
to protect data integrity if there is a power failure.