Hitachi Compute Blade 2000 User Manual page 364

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, 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.
Do not select Write Back with BBU.
Description
Write cache is valid.
Write cache is invalid.
Write cache is valid only when the battery is
installed.
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