From: Harvey, Bruce T. (BTHarvey@LMUS.LEGGMASON.COM)
Date: Mon Dec 15 2003 - 07:24:53 EST
Just as an F.Y.I., we just resolved an issue regarding 'write' performance,
SSARaid with Cache, and the FastWrite feature on disk drives.
We saw performance degradation across the board on all drives connected to
an SSARaid adapter when one of the disks attached didn't have FastWrite
turned on, even though that drive was not involved in disk activity 95% of
the time (a 'dump' filesystem, not involved in normal batch reporting). It
turns out that if even one of your drives does not have the FW feature
turned on, it'll affect the rest of the drives, even those allocated to RAID
arrays on that adapter.
So, to gain the best performance across the board, make sure ALL of your
disks have FW turned on, even if they don't need it.
Just an F.Y.I. from a converted skeptic who saw it with his own eyes.
Bruce T. Harvey
Legg Mason Wood Walker, Inc.
Corporate Technology - UNIX Admin.
Red Run 2nd Floor - Owings Mills, MD
(410) 580-7383 - BTHarvey@LeggMason.com
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