[Linux-cluster] LVM2 cluster safety

[Gordan Bobic]

On Tue, 9 Oct 2007, Darryl Dixon - Winterhouse Consulting wrote:

> I'm trying to understand from the sourcecode and from previous discussions
> on this list exactly which parts of a 'standard' LVM2 setup are 'unsafe'
> in an active/active GFS or OCFS cluster scenario.
>
> In other words, if I have a single LV, in a single VG, on a single PV, on
> a single LUN seen by two hosts via an FC SAN, with GFS or OCFS on top of
> it, and both hosts writing data, and no changes to the VG metadata at all,
> then where are the points of risk?
>
>> From what I can understand of the CLVM daemon, it is entirely concerned
> with serialising ~metadata~ updates, and writes to the LV are assumed to
> be safe as long as they are going through a cluster-aware filesystem on
> top?

My understanding that LVM is not required for clustering, unless you plan 
to grow the FS across multiple volumes. I am not aware of it having a 
functional effect on the functioning of GFS (other than the fact that it 
may need special features to make sure that it is GFS safe).

Gordan