Re: [Linux-cluster] LVM2 cluster safety

[Patrick Caulfield <pcaulfie redhat com>]

Darryl Dixon - Winterhouse Consulting wrote:
> Hi All,
> 
> 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?

That's correct. If you are never going to change the LVM metadata then you don't
need clvm. lvm has no impact on data sharing at all, that's the job of the
filesystem (GFS/OCFS etc).

-- 
Patrick