* RBD image max simultaneous mounts
@ 2012-09-17 2:43 Vladimir Bashkirtsev
2012-09-17 6:55 ` Josh Durgin
0 siblings, 1 reply; 2+ messages in thread
From: Vladimir Bashkirtsev @ 2012-09-17 2:43 UTC (permalink / raw)
To: ceph-devel
Dear devs,
We just had an incident where two instances of the same VM started up on
different hosts and mounted the same RBD image. Image had ext4 partition
and it became corrupted quickly. Therefore it would be good to have some
setting in RBD info like max_simultaneous_mounts which will dictate how
many simultaneous mounts of the same RBD image may be in existence.
Obviously such glusterfs would not have such issue in RBD image but old
trusty extfs fails miserably. It may be hard to implement in ceph due to
distributed nature. Then basic check in QEMU-RBD driver would be good as
well.
Regards,
Vladimir
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: RBD image max simultaneous mounts
2012-09-17 2:43 RBD image max simultaneous mounts Vladimir Bashkirtsev
@ 2012-09-17 6:55 ` Josh Durgin
0 siblings, 0 replies; 2+ messages in thread
From: Josh Durgin @ 2012-09-17 6:55 UTC (permalink / raw)
To: Vladimir Bashkirtsev; +Cc: ceph-devel
On Mon, 17 Sep 2012 12:13:07 +0930, Vladimir Bashkirtsev
<vladimir@bashkirtsev.com> wrote:
> Dear devs,
>
> We just had an incident where two instances of the same VM started up
> on different hosts and mounted the same RBD image. Image had ext4
> partition and it became corrupted quickly. Therefore it would be good
> to have some setting in RBD info like max_simultaneous_mounts which
> will dictate how many simultaneous mounts of the same RBD image may be
> in existence. Obviously such glusterfs would not have such issue in
> RBD image but old trusty extfs fails miserably. It may be hard to
> implement in ceph due to distributed nature. Then basic check in
> QEMU-RBD driver would be good as well.
>
> Regards,
> Vladimir
This is what locking and fencing of rbd images is intended to address.
The original discussion:
http://comments.gmane.org/gmane.comp.file-systems.ceph.devel/7094
The current status:
http://permalink.gmane.org/gmane.comp.file-systems.ceph.devel/9210
Josh
^ permalink raw reply [flat|nested] 2+ messages in thread
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2012-09-17 2:43 RBD image max simultaneous mounts Vladimir Bashkirtsev
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