HP Surestore Disk Array 12h - And FC60 Advanced User's Manual page 302

Disabling Disk Module Write Cache Enable (WCE)
To ensure optimum protection against data loss, it is recommended that Write
Note
Cache Enable be disabled on all disks in the array. Disabling disk WCE will
impact disk array performance. However, it reduces the potential for data loss
during a power loss.
To ensure optimum data integrity, it is recommended that the Write Cache Enable (WCE)
feature be disabled on all disk modules in the array. Each disk has internal write cache
memory which is used to store data until it is written to the disk media. (This should not be
confused with the array controller write cache, which is protected by the BBU.) If power to
a disk is interrupted before data in write cache has been copied to the disk media, the data
will be lost. To avoid this situation, the WCE feature should be disabled on all disks in the
array. This ensures that data is written directly to the disk media and not stored in disk
cache.
This procedure for disabling disk WCE should be executed any time a disk module is
replaced or a new disk module is added to the array. This will ensure that WCE is disabled
on all disks in the array.
To disable WCE on all disks, type:
amutil -w <ArrayID>
WCE will be disabled on all disks visible to the array controllers. Depending on the number
of disk modules in the array, this command can take up to 60 seconds to complete.
Command Example
The following example disables WCE on all disks in disk array 0000005EBD20:
amutil -w 0000005EBD20
Managing the Disk Array Using Array Manager 60
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