From: Spelic <spelic@shiftmail.org>
To: linux-lvm@redhat.com
Subject: [linux-lvm] pvmove painfully slow on parity RAID
Date: Wed, 29 Dec 2010 03:40:47 +0100 [thread overview]
Message-ID: <4D1A9FAF.6050401@shiftmail.org> (raw)
Hello list
pvmove is painfully slow if the destination is on a 6-disks MD raid-5,
it performs at 200-500Kbytes/sec! (kernel 2.6.36.2)
Same for lvconvert add mirror.
Instead, if the destination is on a 4 devices MD raid10near, it performs
at 60MBytes/sec which is much more reasonable. (this is a 120-fold
difference at least!)
Same for lvconvert add mirror.
How come such a difference?
Are you using barriers every tiny block of data maybe? (This could
explain the slowness on parity raid)
If yes, could you use barriers (and hence checkpointing) every, like, 100MB?
(However please note that with lvconvert add mirror I also tried various
--regionsize settings but they don't improve the speed much, i.e. +50%
at most)
Thanks for any information
next reply other threads:[~2010-12-29 2:41 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-29 2:40 Spelic [this message]
2010-12-29 14:02 ` [linux-lvm] pvmove painfully slow on parity RAID Spelic
2010-12-30 2:42 ` Stuart D. Gathman
2010-12-30 3:13 ` Spelic
2010-12-30 19:12 ` Stuart D. Gathman
2010-12-31 3:41 ` Spelic
2010-12-31 15:36 ` Stuart D. Gathman
2010-12-31 17:23 ` Stuart D. Gathman
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