On Mon, Jul 16, 2007 at 10:50:34AM -0500, Eric Sandeen wrote:

David Chinner wrote:

quoted

On Mon, Jul 16, 2007 at 12:41:15PM +1000, David Chinner wrote:

quoted

On Fri, Jul 13, 2007 at 03:36:46PM -0400, Justin Piszcz wrote:

...

quoted

quoted

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