HP Array Controller HSG V8.7 Software - Manual (Page 48)

1–24 HSG80 User’s Guide
Table 1-8 shows the cache policies resulting from full or partial failure
of cache module A’s ECB in a dual-redundant configuration. Note that
when cache module A is at least 50% charged, the ECB is still operable
and charging. When it is less than 50% charged, the ECB is low but still
charging. The consequences shown in this table are reciprocal for a
failure of cache module B’s ECB.
Cache
Board
Failure Good Same as for DIMM failure. Data integrity: Controller A
recovers all of its write-back data
from the mirrored copy on cache B.
Cache policy: Both controllers
support write-through caching only.
Controller B cannot execute
mirrored writes because cache
module A cannot mirror
controller B’s unwritten data.
Failover: No
Table 1-7 Cache Policies and Cache Module Status (Continued)
Cache Module Status Cache Policy
Cache A Cache B Unmirrored Cache Mirrored Cache
Table 1-8 Cache Policies Resulting and ECB Status
Cache Module Status Cache Policy
Cache A Cache B Unmirrored Cache Mirrored Cache
At least
50%
charged At least
50%
charged Data loss: No
Cache policy: Both controllers
continue to support write-back
caching.
Failover: No
Data loss: No
Cache policy: Both controllers
continue to support write-back
caching.
Failover: No