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From: Asdo <asdo@shiftmail.org>
To: Asdo <asdo@shiftmail.org>
Cc: linux-raid <linux-raid@vger.kernel.org>, linux-ext4@vger.kernel.org
Subject: Re: Sync does not flush to disk!?
Date: Fri, 08 Jun 2012 13:39:41 +0200	[thread overview]
Message-ID: <4FD1E47D.2050908@shiftmail.org> (raw)
In-Reply-To: <4FD1CB8A.9080805@shiftmail.org>

On 06/08/12 11:53, Asdo wrote:
> .....
> Then I tried to do :
>
> for i in /dev/md? /dev/sda /dev/sdb ; do blockdev --flushbufs $i ; done
> ....
> and NOW it is seeing the changes.

After some further tests:
Flushbuf'ing just the MD devices only, generated an even more 
intermediate situation in which the file being changed assumed garbage 
content coming from another old file.
Flushbufing just /dev/sda /dev/sdb has worked a few times I tried. I'm 
not sure that it is enough in general.
Flushbufing everything appears to work reliably.

Still I am puzzled. Wasn't "sync" from bash enough to commit to disk 
even in case of power failure?

Or is there any chance that KVM "sees" a version of sda and sdb which is 
actually *older* than the actual content on the platters?

Thank you

  reply	other threads:[~2012-06-08 11:39 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-06-08  9:53 Sync does not flush to disk!? Asdo
2012-06-08 11:39 ` Asdo [this message]
2012-06-08 12:33 ` NeilBrown
2012-06-08 13:49   ` Phil Turmel
2012-06-08 13:57     ` Asdo
2012-06-08 14:11       ` Jan Kara
2012-06-08 14:16         ` Jan Kara
2012-06-08 18:28       ` Ted Ts'o

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