HP StorageWorks HSG80 ACS Solution Software V8.8 for HP-UX Installation and Configuration Guide (AA-RV1FA-TE, March 2005)

Planning a Subsystem
41HSG80 ACS Solution Software V8.8 for HP-UX Installation and Configuration Guide
Enabling Mirrored Caching
In mirrored caching, half of each controller’s cache mirrors the companion
controller’s cache, as shown in Figure 11.
The total memory available for cached data is reduced by half, but the level of
protection is greater.
Figure 11: Mirrored caching
Before enabling mirrored caching, make sure the following conditions are met:
■ Both controllers support the same size cache.
■ Diagnostics indicate that both caches are good.
■ No unit errors are outstanding, for example, lost data or data that cannot be
written to devices.
■ Both controllers are started and configured in failover mode.
What is the Command Console LUN?
StorageWorks Command Console (SWCC) software communicates with the
HSG80 controllers through an existing storage unit, or logical unit number
(LUN). The dedicated LUN that SWCC uses is called the Command Console
LUN (CCL). The CCL serves as the communication device for the HS-Series
Agent and identifies itself to the host by a unique identification string. By default,
a CCL device is enabled within the HSG80 controller on host port 1. The HSG80
uses SCSI-3 with your platform.
Cache module A Cache module B
A
cache
Copy of
B
cache
Copy of
A
cache
B
cache
CXO5729A