RAID Array 410 HSZ40 HSOF Software Version 3.7 for Compaq Tru64 UNIX Release Notes

Release Notes
AA–RMBXA − TE Page 17
5.2.2 Cache Policy
The setting chosen for SET controller CACHE_POLICY (to either A or B)
affects access to RAIDsets and Mirrorsets during the initial test only and
determines the cache mode the controller uses during initial test only.
Initial Test begins when the controller is turned on and continues until the
batteries are charged, or up to ten hours. Initial testing includes a recharge of
the battery after potential discharge during shut down. The battery is tested by
the software every four minutes. Full caching operations begin when the
batteries are fully charged.
Cache Policy A is the default setting. Cache Policy A and B apply only to a
“low” battery situation during controller initialization until either the:
• Battery becomes fully charged or
• 10 hours elapse without the battery becoming fully charged.
In the latter case, failed battery action is taken, as described in the “Failed
Battery Action” section of these release notes.
Once a battery has become fully charged, Cache Policy A and B no longer
applies, and regular periodic battery tests are performed.
Table 5-1 summarizes the effect of both cache policy settings on access to
RAIDsets and mirrorsets when a battery is “low” during the initial test period.
Table 5-1 Cache Policy Settings
Cache Policy RAID/Mirrorset Access Cache Mode
Cache Policy A No access Write-through on individual
disk units
(also called JBOD)
Cache Policy B Access Write-through on
RAID/mirrorsets and
individual disk units