Re: [linux-lvm] has anyone used LVM in a HA cluster?

[Luca Berra <bluca comedia it>]

On Fri, May 10, 2002 at 07:44:44PM -0500, Steven Lembark wrote:
> 
> 
> -- Austin Gonyou <austin coremetrics com>
> 
> >>From what I understand you *can* mount the LVM volumes on multiple hosts
> 
> >at the same time, but you should be *readonly* on the hosts which do not
> >*own* the data on the disks. You could then *remount* the volume on the
> >target failover host.
> 
> I've had reasonable luck with this approach on other
> platforms (HP-UX, but the LVM is similar enough that
> it should work).

well actually a lot of details about the filesystem are cached on
an host, so you get relly funny results when you dont expect
filesystem metadata to change under your nose. I would not be
surprised to see a box panic under these circumstances.

> All it really needs is a "heartbeatd": you open a
> socket to, say, echo (port 1) and every second write
> a byte. If you don't get the byte back in, say, 100ms
> then you try one more time before re-mounting the LV
> rw on the backup host.

there is a tool called heartbeat on http://www.linux-ha.org/
have a look at it it really rocks.
it already has a resource that supports mounting of partitions
on shared media in case an hosts fail, it would be trivial
to adapt it for LVM

L.


-- 
Luca Berra -- bluca comedia it
        Communication Media & Services S.r.l.
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