Specifications

1–2 General Description
The HSG80 Array Controller Subsystem
Take a few moments to familiarize yourself with the major components of the HSG80
array controller subsystem. Figure 1–1 shows the components of a typical installation
that includes:
■ One BA370 rack-mountable enclosure.
■ Two controllers, each supported by a cache module.
■ Two cache modules, which support nonvolatile memory and dynamic cache
policies to protect the availability of its unwritten (write-back) data.
■ Two external cache batteries (ECBs) in one Storage Building Block (SBB),
which provide backup power to the cache modules during a primary power
failure.
■ One environmental monitoring unit (EMU) that monitors the subsystem’s
environment, and alerts the controller of equipment failures that could cause an
abnormal environment.
■ One power verification and addressing (PVA) module that provides a unique
address to each enclosure in an extended subsystem.
■ Six I/O modules that integrate the SSB shelf with either an 8-bit single-ended,
16-bit single-ended, or 16-bit differential SCSI bus.