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The Question is:
What are the consequences of abrupt power failures?
The Answer is :
Most commonly, darkness and quiet -- punctuated by sounds of annoyance
and/or puzzlement, and occasional yelps of pain from bumping into large
and immutable objects prior to the activation of the emergency lights.
Further, abrupt power failures can be viewed as an enabling technology
that is designed to assist in convincing local managment that an
investment in a UPS (Uninterruptable Power Supply) would be fruitful.
In most cases, most applications will recover gracefully from a power
failure, and little more than an ANALYZE/DISK/REPAIR will be needed to
free up existing allocated storage left over from the host caches in
use prior to the power outage.
The results of a power failure can of course vary -- OpenVMS StorageWorks
storage hardware is designed to permit an entire block of data to be
written to completion, and databases and transaction-oriented applications
can be (are) coded to perform all-or-nothing updates -- multi-block disk
writes can obviously fail part way through, should the power fail.
For critical OpenVMS systems, the configuraiton of a UPS, of system
integrated battery backup (for those systems that offer it), a
motor-generator or other alternative power source(s) are typically
recommended for the host system, the peripherals, critical lights,
and for key network hardware, as are batteries for the StorageWorks
enclosures. Discussions of clustering and particularly disaster
tolerant clustering also apply.
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