[pve-devel] VM locked after failed Snapshot

[Stefan Priebe - Profihost AG]

Am 09.09.2014 um 02:11 schrieb Alexandre DERUMIER:
>>> I'm still on 2.0 - did it also exist in 2.0?
> 
> I'm not sure if that bug was present on 2.0.
> 
> just take 1 snasphot with vmstate, then a second snasphot with vmstate.
> 
> 
> (But don't seem related as you take a snasphot without memory state)

At least it has a reference counting bug too. But another one ;-) fixed
that. Will not switch to Qemu 2.1 before 2.1.2. In the first releases
they had too many bugs.

Stefan


> ----- Mail original ----- 
> 
> De: "Stefan Priebe" <s.priebe at profihost.ag> 
> À: "Alexandre DERUMIER" <aderumier at odiso.com> 
> Cc: pve-devel at pve.proxmox.com 
> Envoyé: Lundi 8 Septembre 2014 21:32:04 
> Objet: Re: [pve-devel] VM locked after failed Snapshot 
> 
> Am 08.09.2014 17:18, schrieb Alexandre DERUMIER: 
>> Hi, 
>>
>> my 2cents, but could it be related to the vmstate bug ? 
>> https://git.proxmox.com/?p=pve-qemu-kvm.git;a=commit;h=62d638ff1e9fb96ca078be2225426aaac8f909f6 
> 
> I'm still on 2.0 - did it also exist in 2.0? 
> 
>> (Is a a vm snasphot with vmstate ?) 
> No. 
> 
> Stefan 
> 
>> ----- Mail original ----- 
>>
>> De: "Stefan Priebe - Profihost AG" <s.priebe at profihost.ag> 
>> À: pve-devel at pve.proxmox.com 
>> Envoyé: Lundi 8 Septembre 2014 12:06:48 
>> Objet: [pve-devel] VM locked after failed Snapshot 
>>
>> Hi, 
>>
>> today i had the following problem. 
>>
>> 1.) i wanted to create a snapshot of a vm 
>> 2.) it failed for unknown reason and i had the following output (PVE 
>> Webgui): 
>>
>> image has watchers - not removing 
>> Removing image: 0% complete...failed. 
>> rbd: error: image still has watchers 
>> TASK ERROR: received interrupt 
>>
>> 3.) The VM was than in a locked state (VM is locked (snapshot)) 
>>
>> I see multiple problems here. 
>>
>> 1.) lock state should be removed by PVE in case of a failure. 
>>
>> Currently snapshot_create calls snapshot_prepare to set the lock. And at 
>> the end snapshot_commit deletes the log. 
>>
>> But currently in case of $err 
>>
>> if ($err) { 
>> warn "snapshot create failed: starting cleanup\n"; 
>> eval { snapshot_delete($vmid, $snapname, 0, $drivehash); }; 
>> warn $@ if $@; 
>> die $err; 
>> } 
>>
>> The lock isn't removed. 
>>
>> What is the correct way to remove a lock in this case? 
>>
>> 2.) in case of an unexpected failure or signal ceph/rbd does not remove 
>> it's watcher from the image. So the snapshot_delete failed in this case. 
>>
>> Output: 
>>
>> image has watchers - not removing 
>> Removing image: 0% complete...failed. 
>> rbd: error: image still has watchers 
>>
>> rbd has an automatic timeout after 30s should PVE handle this by waiting 
>> 30s and try it again? 
>>
>> Greets, 
>> Stefan 
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