HP StorageWorks 2000 Series Reference Manual page 59

The disadvantage of ICPM is that if a controller fails, the other controller cannot fail
over (that is, take over I/O processing for the failed controller). If a controller fails,
the host loses access to the volumes owned by that controller. If a controller
experienced a complete hardware failure, and needed to be replaced, then user data
in its write-back cache is lost.
Data loss does not automatically occur if a controller experiences a software
exception, or if a controller module is removed from the enclosure. However, if a
controller is damaged in a nonrecoverable way then you might lose data in ICPM.
Data might be compromised if a RAID controller failure occurs after it
has accepted write data, but before that data has reached the disk drives. Do not use
ICPM in an environment that requires fault tolerance.
Independent cache performance mode disables partner firmware upgrade.
Controllers must be upgraded manually.
To enable or disable Independent Cache Performance Mode:
1. Select Manage > General Config > System Configuration.
2. Click Advanced Options.
3. In the Change Independent Cache Performance Mode panel, select Enabled or
Disabled. The default is Disabled.
4. Click Enable/Disable Independent Cache Performance Mode.
The system automatically restarts both controllers, which takes several minutes to
complete. If ICPM is enabled, this is shown in each page's System Panel and in the
Status Message panel on the Status Summary page.