> Thanks Michael, so the use of the filepool storagepool type does not set
> the O_SYNC flag (and therefor uses the cache on the raid controller) but
a
> normal diskpool does (and therefor doesn't use the cache)?

It's also possible that part of what you are seeing is the Raid5 write
penalty.
The disk pool could be performing random updates around the array.  This
would cause the Raid5 to perform
read(data)-read(parity)-write(date)-write(parity)
cycles for each write. By switching to file pool your writes may be
sequential and
the raid controller may be able to optimize full stripe writes which
avoids
the penalty.  Of course, many concurrent sequential streams to a array can
also
look like random updates.

Rick


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