Re: ATA 4 KiB sector issues.

[Dave Chinner]

On Tue, Mar 09, 2010 at 01:16:01PM +0300, Michael Tokarev wrote:
> Karel Zak wrote:
> > I did almost all my tests with scsi_debug or MD RAID0 on scsi_debug.
> > It works as expected.
> 
> Actually, for raid0, the alignment is questionable.  Should it be a
> multiple of chunk size or whole stripe size?  I'm not sure, both ways
> has bad and good sides..  But if it is the latter, the same issues
> pops up again: do a 3-disk raid0 and you'll have to align to 3*2^N.

Yes, alignment is still needed, especially for filesystems that can
do stripe unit aligned allocation like XFS. If you don't align the
filesystem properly, all the data IO will be mis-aligned to the
underlying disks and stripe unit sized IO will hit multiple disks
rather than just one....

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx
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