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Date:      Fri, 17 Dec 1999 15:13:21 -0500 (EST)
From:      David Gilbert <dgilbert@velocet.ca>
To:        Mike Smith <msmith@freebsd.org>
Cc:        David Gilbert <dgilbert@velocet.ca>, freebsd-current@freebsd.org
Subject:   Re: AMI MegaRAID datapoint. 
Message-ID:  <14426.39265.260916.742812@trooper.velocet.net>
In-Reply-To: <199912172002.MAA00660@mass.cdrom.com>
References:  <14426.20641.329657.464545@trooper.velocet.net> <199912172002.MAA00660@mass.cdrom.com>

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>>>>> "Mike" == Mike Smith <msmith@freebsd.org> writes:

Mike> Try enabling DirectIO and WriteBack if you haven't already.
Mike> AMI's RAID5 implementation seems to suffer from rewriting the
Mike> entire stripe when you do sub-stripe-sized writes, but I'm not
Mike> sure about that yet.

Already done.  This would explain why 128K stripes are bad.

Mike> The Mylex controllers seem to have a small edge in performance,
Mike> which may be due to them doing cache-line-sized I/Os (usually
Mike> only 8k) in that case.

Maybe so, but they also don't seem to support the LVD-enabled versions 
of the Mylex cards.

Dave.

-- 
============================================================================
|David Gilbert, Velocet Communications.       | Two things can only be     |
|Mail:       dgilbert@velocet.net             |  equal if and only if they |
|http://www.velocet.net/~dgilbert             |   are precisely opposite.  |
=========================================================GLO================


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