Re: [Xen-users] Re: cLVM on Debian/Lenny

[John Madden <jmadden@xxxxxxxxxxx>]

> I think of cLVM as the LVM with the cluster extension. Any setting on
> a
> shared storage is visible by all the nodes of the cluster.
> But what exactly does this mean? At which level (VG or LV) does the
> locking library work? Can I enable (active) the same VG on different
> nodes? If yes, how cLVM prevent split-brain? I would eventually be
> able
> to load a LV only on one node?

cLVM just keeps LVM changes consistent across the cluster.  It's a
system of locks (via dlm) that prevents one node from making LVM changes
while another node is making them.  You can mount a LV on multiple nodes
simultaneously and completely trash your data if you like -- clvm
doesn't prevent this -- and in fact this behavior is necessary if you're
going to use a cluster filesystem such as OCFS or GFS.

John




-- 
John Madden
Sr UNIX Systems Engineer
Ivy Tech Community College of Indiana
jmadden@xxxxxxxxxxx


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