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Date: Fri, 15 Mar 2013 12:29:01 +0300
From: Vladislav Bogdanov <bubble@hoster-ok.com>
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Subject: Re: [linux-lvm] LVM snapshot with Clustered VG [SOLVED]
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To: Zdenek Kabelac <zkabelac@redhat.com>
Cc: Andreas Pflug <pgadmin@pse-consulting.de>, LVM general discussion and development <linux-lvm@redhat.com>

15.03.2013 12:00, Zdenek Kabelac wrote:
> Dne 14.3.2013 22:57, Andreas Pflug napsal(a):
>> On 03/13/13 19:30, Vladislav Bogdanov wrote:
>>>
>>>> Is there a way to find out if a LV is locked exclusively? lvs
>>>> displaying
>>>> -e-- instead of -a-- would be nice. Seems not even lvdisplay knows
>>>> about
>>>> exclusive locking.
>>> That would break other tools which rely on their output. F.e. cluster
>>> resource agents of libvirt (yes, it runs lvm tools rather then using
>>> API, which is not yet complete btw). As I also need to obtain this
>>> information, I think about writing simple tool (f.e. clvm_tool) which
>>> would display needed info.
>>>
>>> As a workaround you can run lvchange -aly without force parameter. If it
>>> succeeds, the volume is locked in a shared mode, otherwise it is locked
>>> exclusively.
>>
>> Hm, thats one ugly workaround...
>> How about a clvmd option, something like -l to list all locks and exit.
>>
> 
> 
> I think - the extension to  'lvs' command could be relatively simple
> (adding a new column)

Yes, that's correct.

> 
> You may query  for  exclusive/local activation on the node.
> (So you cannot just tell on which other node is the device active,
> but you could print about these states:
> 
> active exclusive local
> active exclusive
> active local
> active

You also may poll all know nodes, but that is a hack too.

That's why I prefer to have this as a separate tool (with dlm_tool-like
params and output) which lists node IDs and lock mode. Unfortunately do
not have power to write it now.

Are core LVM devels interested in these two features: lock conversion
and managing remote node locks? If yes, then I can (hopefully) prepare
git patches next week.

Vladislav