Hitachi Compute Blade 2000 User Manual page 438

 Changing the write policy for disk arrays
This section describes the procedure for changing the write policies.
Enabling Write Cache of a disk array can improve the write performance.
When enabling the disk array "write cache" with the equipment that has no
cache backup module installed, connect the system equipment to UPS.
Otherwise, data in the write cache may disappear or be destroyed during a
blackout or instant power failure.
In Write Policy for the equipment that has no

cache backup module installed, Always Write
Back can be supported only when the system
equipment is connected to the UPS
(uninterruptible power supply).
Even in this case, set to Write Through when
installing the operating system. Otherwise,
installation may not be properly completed.
When the equipment has a cache backup module

installed, make sure to set Write Back With BBU
for Write Policy. If not, write performance may
slow down.
1 Select Virtual Drives in the main menu.
The following screen appears:
NOTICE
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