Very bad FreeBSD SCSI RAID5 write speed performance

[Allen Briggs]

On Thu, Nov 13, 2003 at 06:38:53AM -0500, Gary Stanley wrote:
> root at 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 at wasabisystems.com
 Wasabi Systems, Inc.             http://www.wasabisystems.com/