Compaq HSZ80 manual Cache Policies and Cache Module Status

1–23

Table 1–9shows the cache policies resulting from a full or partial failure of cache module A’s ECB in a dual-redundant controller configuration. When cache module A is at least 50% charged, the ECB is still good and is charging. When it is less than 50% charged, the ECB is low, but still charging. The consequences shown are the opposite for a failure of cache module B’s ECB.

Table 1–8 Cache Policies and Cache Module Status

Cache Module Status		Cache Policy
Cache A	Cache B	Unmirrored Cache	Mirrored Cache
Good	Good	Data loss: No.	Data loss: No.
		Cache policy: Both controllers	Cache policy: Both controllers support
		support write-back caching.	write-back caching.
		Failover: No.	Failover: No.
Multibit	Good	Data loss: Forced error and loss of	Data loss: No. Controller A recovers its
cache		write-back data for which the	lost write-back data from the mirrored
memory		multibit error occurred. Controller A	copy on cache B.
failure		detects and reports the lost blocks.	Cache policy: Both controllers support
		Cache policy: Both controllers	write-back caching.
		support write-back caching.	Failover: No.
		Failover: No.

Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide