[Linux-cluster] LVM2 cluster safety

[Darryl Dixon - Winterhouse Consulting]

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?


many regards,
Darryl Dixon
Winterhouse Consulting Ltd
http://www.winterhouseconsulting.com