Recovering Data From The Controller's Cache - HP D7171A - NetServer - LPr Installation Manual

Hewlett-Packard NetRAID-4M Controller Installation Guide
Note:
The controller must first be opened for writing before
you can initiate a battery reconditioning.
To schedule a reconditioning cycle for a future time (on Windows
NT only), create an AT batch file with the appropriate CLI
command. You should try to complete the reconditioning sometime
during the week that follows the first notification you receive. The
HP NetRAID-4M host driver and FAST will continue to remind you
periodically that a reconditioning is still needed, so you won't
forget.
Note:
During the reconditioning cycle, which takes
approximately 6 to 10 hours, the controller automatically
disables cache to ensure that no data is lost. Performance is
degraded during this period. Once the reconditioning cycle
is complete, the cache is restored to its original settings.
If the system is powered off during a reconditioning, it will be
necessary to manually restart the reconditioning. If possible, avoid
shutting down the system until the reconditioning cycle completes.

Recovering Data from the Controller's Cache

The HP NetRAID-4M controller is designed to ensure no loss of
data, even under various failure conditions. The controller's
Daughter Card contains both the cache memory (DIMM) and
battery subsystem as an integrated unit, allowing the Daughter
Card's cache to be preserved even when the Daughter Card is
removed from the controller card.
If your system loses power, for example, and the controller is not
damaged (and the battery holdover time has not been exceeded), the
cache is flushed to disk after the controller finishes its power-on-self-
test.
If, however, you determine that your controller suffered a hardware
failure — for example, you receive a hardware failure message
during the HP NetRAID-4M power-on self-test — and data in the
cache was not flushed to disk prior to the failure, data remains in the
cache. To prevent loss of this data, you must flush the controller's
cache, even though the main controller is no longer operational.
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