Re: Sanlock gives up lock when VM is paused

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In doing more testing I notice that the resource listed by 'sanlock client status' disappears when the VM is paused. I haven't yet found anything about lock versions yet though.

However, even if sanlock behaved as you said, preventing the unpausing of a VM once another one has used it's disk, this could still cause damage to the filesystem if the VM is paused during write operations and never allowed to finish (after the subsequent VM using the same storage takes over). I would think the ideal behavior would be keeping the lock until the VM is completely off. I don't see why this would get in the way of migration as the filesystem shouldn't need to be accessed until the RAM contents have been migrated to the other machine, but then again I'm not writing the code.


Thanks,
Michael

On 1/31/2013 3:56 PM, Michael Rodrigues wrote:
Just for follow up and future reference:

https://bugzilla.redhat.com/show_bug.cgi?id=906590

Thanks,
Michael

On 1/31/2013 12:03 PM, Daniel P. Berrange wrote:
On Thu, Jan 31, 2013 at 11:02:15AM -0800, Michael Rodrigues wrote:
On 1/31/2013 10:40 AM, Daniel P. Berrange wrote:
On Thu, Jan 31, 2013 at 10:35:17AM -0800, Michael Rodrigues wrote:
Hi Daniel,

I thought migration might be the reason, but I'm still not seeing
the behavior you describe with regards to pausing. I saw the
following behavior:

1. Created VM on node 1
2. Started VM on node 1
3. Migrated VM to node 2, node 1 is now shutdown, node 2 is running
4. I paused node 2
5. I started node 1, no error
6. Paused node 1
7. Unpaused node 2, no err

I thought maybe the original VM had to be paused first, so I tried
that as well:

1. Created VM on node 1
2. Started VM on node 1
3. Migrated to node 2, node 1 is now shutdown, node 2 is running
4. I shutdown node 2 instead of pausing
5. I started node 1
6. I paused node 1
7. Started node 2
8. Paused node 2
9. Started node 1
Hmm, that isn't supposed to be possible. When you paused node 1
in step 6, it was supposed to record the lease version number.
When you resume in step 9, the version number should mis-match
due to step 7, and thus sandlock ought to have caused an error
at step 9. If that didn't happen, then I believe we have a bug
Should I file a report? I'm not really a developer but I can provide
whatever information is necessary for a proper report. I don't have
RHEL or a bugzilla account.
Yes, please do file a bug report including this scenario to
reproduce

Daniel




--
Michael Rodrigues
Interim Help Desk Manager
Gevirtz Graduate School of Education
Education Building 4203
(805) 893-8031
help@xxxxxxxxxxxxxxxxxx

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