Specifications

2–13
Compaq HSG80 Array Controller ACS Version 8.4 Configuration and CLI Reference Guide
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 2–2. Cache Policies and Cache Module Status (Continued)
Cache Module Status Cache Policy
Cache A Cache B Unmirrored Cache Mirrored Cache