[Ocfs2-users] Query regarding OCFS2 and RHEL4 LVM

[Joel Becker]

On Tue, Jul 08, 2008 at 05:36:48PM +0100, Pedro Figueira wrote:
> Why do you consider the LVM2 not cluster safe? Is it just because you should not (can't) modify any LVM configuration with the volume groups activated in more than one server?

	Not only can you not modify it, there are also configurations
where the LVM2 code will do modifications behind your back - and the
other nodes don't know about it.  For example, dm-mirror keeps track of
changes that have only hit one copy so far.  Another node might read the
un-updated copy before it has been updated by the writing node.  That's
not safe.
	We consider data integrity of paramount importance.  Trying to
configure LVM2 (non-clustered) to make sure nothing will change is not
trivial.  We won't recommend it, knowing that it just takes one admin
who isn't paying attention to wipe out your entire volume.

Joel

-- 

"Only a life lived for others is a life worth while."
							-Albert Einstein  

Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker at oracle.com
Phone: (650) 506-8127