Re: 3ware 9650 tips

[David Chinner <dgc@sgi.com>]

On Mon, Jul 16, 2007 at 10:50:34AM -0500, Eric Sandeen wrote:
> David Chinner wrote:
> > On Mon, Jul 16, 2007 at 12:41:15PM +1000, David Chinner wrote:
> >> On Fri, Jul 13, 2007 at 03:36:46PM -0400, Justin Piszcz wrote:
> ...
> >> If you've got any sort of serious disk array, ext3 is not the filesystem
> >> to use....
> > 
> > To show what the difference is, I used blktrace and Chris Mason's
> > seekwatcher script on a simple, single threaded dd command on
> > a 12 disk dm RAID0 stripe:
> > 
> > # dd if=/dev/zero of=/mnt/scratch/fred bs=1024k count=10k; sync
> > 
> > http://oss.sgi.com/~dgc/writes/ext3_write.png
> > http://oss.sgi.com/~dgc/writes/xfs_write.png
> 
> Were those all with default mkfs & mount options?  ext3 in writeback
> mode might be an interesting comparison too.

Defaults. i.e.

# mkfs.ext3 /dev/mapper/dm0

# mkfs.xfs /dev/mapper/dm0

The mkfs.xfs picked up sunit/swidth correctly from the dm volume.

Last time I checked, writeback made little difference to ext3 throughput;
maybe 5-10% at most. I'll run it again later today...

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group