Hitachi Compute Blade 2000 User Manual page 439

2 From the list displayed at the upper right of the screen, select a disk array for
which you want to change the write policy. Check Properties and click Go.
The following screen appears:
3 Select the write policy from Default Write in the Policies pane, and click
Change.
Setting value
Always Write Back
Write Through
Write Back with BBU
In Write Policy for the equipment that has no

cache backup module installed, operation with
Always Write Back can be supported only when
the system equipment is connected to the UPS
(uninterruptible power supply). Even in this case,
set Write Through when installing OS.
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.
Description
Write cache is valid.
Write cache is invalid.
Write cache is valid only when a cache backup
module is installed.
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