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Re: [linux-lvm] LVM snapshot with Clustered VG [SOLVED]



Dne 15.3.2013 10:29, Vladislav Bogdanov napsal(a):
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.


I'm not quite sure what do you mean by  'managing remote node locks' ?

Current login behind lvm command is  -

You could activate LVs with the above syntax [ael]
(there is a tag support - so you could exclusively activate LV on remote
node in via some configuration tags)

And you want to 'upgrade' remote locks to something else ?

What would be the use-case you could not resolve with current command line args?

Is that supported by dlm (since lvm locks are mapped to dlm)?
How would you resolve error path fallbacks ?
Also I believe the clvmd protocol is out of free bits for extension,
so how the protocol would look like ?

Zdenek


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