Specifications

2–16 Controller and Host Concepts
Failed At least
50%
charged
Data loss: No
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.
In single configurations, the controller
only provides write-through caching to
its units.
Data loss: No
Cache policy: Both controllers
continue to support write-back
caching.
Failover: No
Less than
50%
charged
Less than
50%
charged
Data loss: No
Cache policy: Both controllers support
write-through caching only.
Failover: No
Data loss: No
Cache policy: Both controllers
support write-through caching
only.
Failover: No
Table 2–3. Resulting Cache Policies and ECB Status (Continued)
ECB Status Cache Policy
Cache A Cache B Unmirrored Cache Mirrored Cache