From: Neil Brown <neilb@suse.de>
To: Justin Maggard <jmaggard10@gmail.com>
Cc: linux-raid@vger.kernel.org
Subject: Re: Sysfs update frequency
Date: Wed, 17 Mar 2010 08:52:56 +1100 [thread overview]
Message-ID: <20100317085256.6caee9bb@notabene.brown> (raw)
In-Reply-To: <150c16851003161432gf38c0f5o1cc957435efd4c3e@mail.gmail.com>
On Tue, 16 Mar 2010 14:32:55 -0700
Justin Maggard <jmaggard10@gmail.com> wrote:
> I've noticed on recent kernels that /sys/block/md?/md/sync_completed
> seems to rarely get updated. What is the expected update interval?
> For me, it seems to only update about once every 6% or so during the
> resync. Of course, /proc/mdstat has the actual current progress.
The expected update time is every 6% - actually 1/16 which is 6.25%.
sync_completed includes a guarantee that all blocks before this point really
have been processed. The number in /proc/mdstat is less precise. The much
of the array has been resynced, but due to the possibility of out-of-order
completion of writes they may not be a contiguous series of blocks.
Providing the guarantee (which is needed for externally-managed metadata)
requires briefly stalling the resync, so I didn't want to do it more often.
I could possibly make it time-bases instead of size-based though.
Is this a problem for you?
NeilBrown
next prev parent reply other threads:[~2010-03-16 21:52 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-16 21:32 Sysfs update frequency Justin Maggard
2010-03-16 21:52 ` Neil Brown [this message]
2010-03-16 22:25 ` Justin Maggard
2010-03-16 23:03 ` Michael Evans
2010-03-20 16:48 ` Bill Davidsen
2010-03-23 3:22 ` Neil Brown
2010-03-24 19:49 ` Bill Davidsen
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