Re: [pve-devel] Consistency in volume deletion in process of concurrent VM deletion

["Fabian Grünbichler" <f.gruenbichler@proxmox.com>]

On October 22, 2025 4:38 pm, Andrei Perepiolkin wrote:
> Hi Fabian,
> 
> 
> I can try to prototype some proof-of-concept solution for 'lock 
> granularity'.

see https://pve.proxmox.com/wiki/Developer_Documentation for details of
how to submit patches (in particular also "Software License and
Copyright").

> Once it is done, the issue of ssh session termination should become clear.

it would be interesting, because right now I don't really see how a `qm`
invocation should kill the SSH session it is running in - it definitely
should not happen!

> Im new to mail-based contribution and Proxmox code itself.
> So I will probably have questions on various topics.
> 
> Should I send this questions via email, as messages in bugzila or via 
> other tool?

questions regarding patch development (both the workflow, and the patch
contents) are probably best discussed here on the list. feel free to
continue this thread, unless it is a very generic question.

> On 10/22/25 05:49, Fabian Grünbichler wrote:
>> On October 21, 2025 5:33 pm, Andrei Perepiolkin via pve-devel wrote:
>>> Hi Proxmox Community,
>>>
>>> There might be a potential consistency problem with Proxmox vm deletion.
>>>
>>> If Proxmox receives multiple concurrent VM deletion requests, where each
>>> VM has multiple disks located on shared storage.
>>>
>>> The deletion process may fail or hang when attempting to acquire the
>>> storage
>>> lock(https://github.com/proxmox/pve-storage/blob/master/src/PVE/Storage.pm#L1196C1-L1209C7).
>>>
>>> ...
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> cfs-lock 'storage-jdss-Pool-2' error: got lock request timeout
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> cfs-lock 'storage-jdss-Pool-2' error: got lock request timeout
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> trying to acquire cfs lock 'storage-jdss-Pool-2' ...
>>> cfs-lock 'storage-jdss-Pool-2' error: got lock request timeout
>>> ...
>>>
>>> Eventually, the VM configuration files in /etc/pve are removed, but some
>>> VM disks may remain.
>>>
>>> Additionally, the Web UI shows all deletions as successful, even though
>>> some disks were not deleted.
>>>
>>> In my opinion, a VM should either be deleted completely—including all
>>> dependent resources—or the deletion should fail, leaving the VM
>>> configuration file with an updated state.
>> the underlying issue is that the scope of the lock taken for certain
>> storage operations is very big for shared storages. we could probably
>> reduce it to a more meaningful level for most such storages:
>>
>> https://bugzilla.proxmox.com/show_bug.cgi?id=1962
>>
>> but the the error handling might also be lacking in this case, would
>> have to double-check.
>>
>>> Im reproducing this by:
>>>
>>>       for i in `seq 401 420` ; do  qm clone 104 $i --name "win-$i" --full
>>> --storage jdss-Pool-2 ; done;
>>>
>>>       for i in `seq 401 410` ; do  qm destroy $i
>>> --destroy-unreferenced-disks 1 --purge 1 &  done ;
>>>
>>>
>>> Have to notice that ssh session that I use to conduct 'qm destroy'
>>> command get terminated by Proxmox.
>> that seems unexpected, are you sure this is caused by PVE?
>>
>>> Ive duplicated as a bug at:
>>> https://bugzilla.proxmox.com/show_bug.cgi?id=6957
>> it would be better to either send a mail or file a bug, to not risk
>> splitting the discussion..
>>
>>> Is this a bug and will it be addressed in near future?
>> nobody picked up the work regarding the lock granularity, but it would
>> be a nice improvement IMHO!
>>
>> Fabian
>>
> 
> 


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