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Date: Thu, 13 Nov 2003 08:23:27 -0500
From: Allen Briggs <briggs@wasabisystems.com>
To: Gary Stanley <gary@outloud.org>
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cc: freebsd-scsi@freebsd.org
cc: Martin Blapp <mb@imp.ch>
Subject: Re: Very bad FreeBSD SCSI RAID5 write speed performance
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On Thu, Nov 13, 2003 at 06:38:53AM -0500, Gary Stanley wrote:
> root@64:[/tmp/blah]>dd if=/dev/zero of=/tmp/blah/blah
> 89472+0 records in
> 89471+0 records out
> 45809152 bytes transferred in 8.546312 secs (5360108 bytes/sec)

I suspect you know this, but if you give a larger block size (bs=...),
you should see better performance.  Writing to a file on the filesystem
not only brings up the softupdates question, but also your choices for
block and fragment sizes.  On a RAID, there's also the question of
stripe size and how that's set with respect to the filesystem block
and fragment sizes.

-allen

-- 
 Allen Briggs                     briggs@wasabisystems.com
 Wasabi Systems, Inc.             http://www.wasabisystems.com/