Very bad FreeBSD SCSI RAID5 write speed performance

[Gary Stanley]

Yeah, It was early in the morning, I was doing a bunch of IOS upgrades most 
of the night. :)

 >dd if=/dev/zero of=./test bs=128k count=2000
2000+0 records in
2000+0 records out
262144000 bytes transferred in 18.012217 secs (14553678 bytes/sec)

Not bad. That's what I'm expecting. :)





At 08:23 AM 11/13/2003, you wrote:
>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/