On Sun, 28 Feb 2010, Bill Davidsen wrote:

Justin Piszcz wrote:

quoted

On Sun, 28 Feb 2010, Mike Snitzer wrote:

quoted

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

[ .. ]

quoted

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.

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I'm going to have to do some testing now, I just tested ext4 against the raw 
speed of the device (single device test) and they were quite close to 
identical. I'm going to order one more drive to bring my test setup up to 
five devices, and do some testing on how it behaves.

More later.

Thanks, let me know how it goes, I see the same thing, on a single hard 
drive, there is little difference between EXT4 and XFS:
http://permalink.gmane.org/gmane.linux.kernel/955357

However, when multiple disks are involved, it is a different story.

Justin.