HP P3410A - NetRAID 1M RAID Controller Installation And Configuration Manual page 45

Chapter 4
Write Policy
!
When the IOP writes to disk, the data is first written to the cache on the
assumption that the IOP will read it again soon. The two Write policies are:
Write-Through: In a write-through cache, data is written to disk at the
same time it is cached. This setting provides better security because
entries are always copied to disk. Unless an Uninterruptible Power Supply
(like a battery backup unit) is connected, you should use the write-through
setting, because otherwise data could be lost from cache memory in the
event of a power failure.
NOTE
Write-Back: In a write-back cache, data is written to disk only when it is
forced out of the cache. Write-back is efficient, because an entry may be
written many times in the cache without a disk access. Write-Back can be
used if an Uninterruptible Power Supply maintains the data in cache
memory in case of a power failure.
NOTE
For each logical drive, record the write policy in Worksheet B.
Write-Through is the recommended write policy for the
HP NetRAID-1M adapter because this adapter does not have a
battery backup unit.
Write-Back is NOT recommended unless one of the following
is true:
The adapter is HP NetRAID-2M with a battery backup
unit.
The system has an uninterruptible power supply (UPS).
Write-Back is not certified for any logical drive used as a
Novell NetWare volume.
Planning
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