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From: Richard Scobie <richard@sauce.co.nz>
To: xfs@oss.sgi.com
Subject: XFS over LVM over md RAID
Date: Fri, 10 Sep 2010 10:58:22 +1200	[thread overview]
Message-ID: <4C89668E.6010800@sauce.co.nz> (raw)

Using the latest, stable versions of LVM2 and xfsprogs and the 2.6.35.4 
kernel, I am setting up lvm on a 16 drive, 256k chunk md RAID6, which 
has been used to date with XFS directly on the RAID.

mkfs.xfs directly on the RAID gives:

meta-data=/dev/md8               isize=256    agcount=32, 
agsize=106814656 blks
          =                       sectsz=4096  attr=2
data     =                       bsize=4096   blocks=3418068864, imaxpct=5
          =                       sunit=64     swidth=896 blks
naming   =version 2              bsize=4096   ascii-ci=0

which gives the correct sunit and swidth values for the array.

Creating an lv which uses the entire array and mkfs.xfs on that, gives:

meta-data=/dev/vg_local/Storage  isize=256    agcount=13, 
agsize=268435455 blks
          =                       sectsz=512   attr=2
data     =                       bsize=4096   blocks=3418067968, imaxpct=5
          =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0

Limited testing using dd and bonnie++ shows no difference in write 
performance whether I use sunit=64/swidth=896 or sunit=0/swidth=0 on the lv.

My gut reaction is that I should be using 64/896 but maybe mkfs.xfs 
knows better?

Regards,

Richard

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             reply	other threads:[~2010-09-09 22:57 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-09 22:58 Richard Scobie [this message]
2010-09-10  0:25 ` XFS over LVM over md RAID Michael Monnerie
2010-09-10  0:52   ` Richard Scobie
2010-09-10  1:14   ` Richard Scobie
2010-09-10  1:30 ` Dave Chinner
2010-09-10  2:29   ` Richard Scobie
2010-09-10 14:24     ` Eric Sandeen
2010-09-10 21:42       ` Richard Scobie
2010-09-10 22:19         ` Stan Hoeppner
  -- strict thread matches above, loose matches on Subject: below --
2010-09-10 23:08 Richard Scobie

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