Browse Prior Art Database

Low Power, Fault Tolerant Parallel Data Dump Following Power Failure

IP.com Disclosure Number: IPCOM000115657D
Original Publication Date: 1995-Jun-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 78K

Publishing Venue

IBM

Related People

Mattson, RL: AUTHOR [+2]

Abstract

It is rapidly becoming common practice to use battery backed-up memory to hold critical data in many computer systems and/or sub-systems. Non-volatile memory in Disk array controllers is a current example of such a situation. If power should fail, the battery should hold the critical information in memory and power one or more disk drives until the critical data has been dumped from the memory to the non-volatile disk storage. For very critical data, it is felt that the critical data should be dual-copied on 2 disk drives so that if one disk drive fails, the system can still be re-started. If there are N blocks of critical data, battery power must be sufficient to power memory and 2 disk drives until N blocks of data can be dumped to each drive.

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This is the abbreviated version, containing approximately 52% of the total text.

Low Power, Fault Tolerant Parallel Data Dump Following Power Failure

      It is rapidly becoming common practice to use battery backed-up
memory to hold critical data in many computer systems and/or
sub-systems.  Non-volatile memory in Disk array controllers is a
current example of such a situation.  If power should fail, the
battery should hold the critical information in memory and power one
or more disk drives until the critical data has been dumped from the
memory to the non-volatile disk storage.  For very critical data, it
is felt that the critical data should be dual-copied on 2 disk drives
so that if one disk drive fails, the system can still be re-started.
If there are N blocks of critical data, battery power must be
sufficient to power memory and 2 disk drives until N blocks of data
can be dumped to each drive.

      If for any number of reasons the battery power cannot last that
long, data will be lost, so the battery backup system is usually over
designed to minimize the risk.

      This invention relates to dumping one copy of critical data as
rapidly as possible with as little power as possible.  Multiple
copies, one after the other, are dumped so that data is M-copied on
D>=M disks if battery power meets expectations and system re-start is
possible even if M-1 disks fail.

      Based on the assertion that, because of the inertia of spinning
disks, it takes less power to maintain D disks for N/D seconds than
to maintain 1 disk for N seconds, the concept of dumping one copy of
critical data as rapidly as possible with as little power as possible
is achieved by separating the N blocks of critical data into D
disjoint groups, group-1, group-2, ..., group-D, of N/D blocks each.
The...