[linux-lvm] Docs on clustered option of vgcreate

Patrick Caulfeld pcaulfie at redhat.com
Fri Feb 8 08:31:17 UTC 2008

Gerrard Geldenhuis wrote:
> Excellent, thanks for the answer, that makes it a lot clearer.
> So coupled with exclusion lists etc.. I could have multiple machines
> connect to one LUN and each have its own logical volume. Is there a
> concept of a “master” in the cluster or does it work in the same way as
> tcp with an exponential backoff when the metadata is locked by a host
> for changing. I am assuming that cluster aware locking would allow
> server-a to create a new lv but not simalteneosly allowing server-b to
> create a new lv too.
> I know should be experimenting with this but will ask in the mean time
> while I wait for my “test lun”.
> If host A creates a lv on a shared storage will it automatically be
> marked as only belonging to host A or is that something you have to do
> by hand. I read somewhere in the man pages about tags that you need to
> add to achieve such things.

Locking in CLVM is exclusive and there's no back off. There is no reason
for it, creating an LVM doesn't take very long and is done from a
command-line. Host 'b' will simply wait until host 'a' has finished its job.

If you need to mark LVs to be exclusive to a node you will need to use
tags to define which node is allowed access

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