[linux-lvm] the lvm shared storage question of the week

[John Leach]

On Wed, 2008-08-06 at 08:38 +0200, Jean Spirat wrote:

Hi,

> > LVM manual briefly mentions CLVM (should apply equally well to debian):
> > http://www.redhat.com/docs/manuals/enterprise/RHEL-5-manual/Cluster_Logical_Volume_Manager/index.html 
> >
> yes it just speak about it but there is no doc at all, nothing tells us 
> if it listen on a tcp port or just communicate by using data on the disk 
> or anything about the setup. Also it speak about special configuration 
> in lvm.conf but nowhere i see WHAT should be configured :)

CLVM needs a distributed lock manager to work (which communicates over
the network, not via the disk).  This is usually provided with the help
of the RedHat Cluster Suite.

>that it should use
>
>locking_type=2
>
>but is this enough ?

by default, locking type 2 or 3 requires clvmd, which as I say will
require a cluster setup of some kind.

You *can* work without a cluster manager but I'm not sure how advised it
is.  So you leave your locking type as 1 and use "lvchange
--refresh /dev/vg/*" on all nodes to reload metadata from disk whenever
you make a change.  Can be a bit risky.

John.
-- 
http://johnleach.co.uk