On Sun, 28 Feb 2010, Mike Snitzer wrote:

On Sun, Feb 28, 2010 at 4:45 AM, Justin Piszcz [off-list ref] wrote:

[ .. ]

How did you format the ext3 and ext4 filesystems?

Did you use mkfs.ext[34] -E stride and stripe-width accordingly?
AFAIK even older versions of mkfs.xfs will probe for this info but
older mkfs.ext[34] won't (though new versions of mkfs.ext[34] will,
using the Linux "topology" info).

Yes and it did not make any difference:
http://lkml.org/lkml/2010/2/27/77

Incase anyone else wants to try too, you can calculate by hand, or if you
are in a hurry, I found this useful:
http://busybox.net/~aldot/mkfs_stride.html

I believe there is something fundamentally wrong with ext4 when performing 
large sequential I/O when writing, esp. after Ted's comments.

Justin.