[lkml]   [2010]   [Mar]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: ATA 4 KiB sector issues.
Dave Chinner wrote:
> 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....

I understand alignment is needed, the question is if the alignment
should be to chunk size or full-stripe size. In neither case it
will be bad for underlying disks.


 \ /
  Last update: 2010-03-09 12:41    [W:0.131 / U:32.240 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site