Re: [Xen-users] High availability and live migration with just LVM and hardware fencing

[Bart Coninckx <bart.coninckx@xxxxxxxxxx>]

On Wednesday 19 May 2010 11:46:18 Bart Coninckx wrote:
> Hi all,
> 
> I've been studying some tutorials and howtos about Xen Live Migration and
>  High Availability in preparation for my new setup (which should do both).
> 
> I like the KISS principle (Keep It Simple, Stupid) and I was thinking about
> using iSCSI LUNs on which I would create LVM logical volumes to be used as
> block devices for Xen hosts after being activated in evry individual host.
> I've tested this for Live Migration and that seems to work flawlessly.
> 
> So i figured I could use this as well for HA. Of course in order to prevent
> several Xen hosts actively accessing the same block devices, I would use
> Heartbeat 2 and hardware fencing to kill a host reporting an unstable
>  state.
> 
> However, I see a lot of references to using cLVM or EMVS when sharing
>  storage. Is this really necessary in my setup? I would like to avoid the
>  added complexity. Also, I'm using SLES10 and cLVM is not supported on that
>  yet, while EVMS is going to be phased out on this distro. OCFS2 seems only
>  usefull when using file based images, which I won't.
> 
> 
> Thx!!!
> 
> 
> Bart
> 
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> 

Did some further research in the meantime and so far the best reason I can 
find for using cLVM, is the making changes to the volume groups: with cLVM 
they seem to be "published" to all Xen hosts at once, while with LVM one needs 
to reconnect to the volume group (probably causing weird things to the 
guests).

Still open to your comments,


Bart

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