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 -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
