HP Array Controller HSG V8.7 Software - Manual (Page 47)

General Description 1–23
DIMM or
cache
memory
controller
chip
failure Good Data integrity: Write-back data
that was not written to media when
failure occurred was not
recovered.
Cache policy: Controller A
supports write-through caching
only; controller B supports write-
back caching.
Failover: In transparent failover,
all units failover to controller B. In
multiple-bus failover with host-
assist, only those units that use
write-back caching, such as
RAIDsets and mirrorsets, failover
to controller B. All units with lost
data become inoperative until you
clear them with the CLEAR
LOST_DATA command. Units
that didn’t lose data operate
normally on controller B.
In single controller configurations,
RAIDsets, mirrorsets, and all units
with lost data become inoperative.
Although you can clear the lost
data errors on some units,
RAIDsets and mirrorsets remain
inoperative until you repair or
replace the nonvolatile memory on
cache A.
Data integrity: Controller A
recovers all of its write-back data
from the mirrored copy on cache B.
Cache policy: Controller A
supports write-through caching
only; controller B supports write-
back caching.
Failover: In transparent failover, all
units failover to controller B and
operate normally. In multiple-bus
failover with host-assist, only those
units that use write-back caching,
such as RAIDsets and mirrorsets,
failover to controller B.
Table 1-7 Cache Policies and Cache Module Status (Continued)
Cache Module Status Cache Policy
Cache A Cache B Unmirrored Cache Mirrored Cache