HP Array Controller HSG V8.7 Software - Manual (Page 46)

1–22 HSG80 User’s Guide
THIS CONTROLLER CACHE_UPS command. See Appendix B, “CLI
Commands,” for instructions on using this command.
Cache Policies Resulting from Cache Module Failures
If the controller detects a full or partial failure of its cache module or
ECB, it automatically reacts to preserve the unwritten data in its cache
module. Depending upon the severity of the failure, the controller
chooses an interim caching technique (also called the cache policy)
which it uses until you repair or replace the cache module or ECB.
Table 1-7 shows the cache policies resulting from a full or partial
failure of cache module A in a dual-redundant controller configuration.
The consequences shown in this table are the same for cache module B.
Table 1-7 Cache Policies and Cache Module Status
Cache Module Status Cache Policy
Cache A Cache B Unmirrored Cache Mirrored Cache
Good Good Data loss: No
Cache policy: Both controllers
support write-back caching.
Failover: No
Data loss: No
Cache policy: Both controllers
support write-back caching.
Failover: No
Multibit
cache
memory
failure Good Data loss: Forced error and loss of
write-back data for which multibit
error occurred. Controller A
detects and reports the lost blocks.
Cache policy: Both controllers
support write-back caching.
Failover: No
Data loss: No. Controller A
recovers its lost write-back data
from the mirrored copy on cache B.
Cache policy: Both controllers
support write-back caching.
Failover: No