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Re: [Xen-users] iscsi vs nfs for xen VMs

To: James Harper <james.harper@xxxxxxxxxxxxxxxx>
Subject: Re: [Xen-users] iscsi vs nfs for xen VMs
From: Pasi Kärkkäinen <pasik@xxxxxx>
Date: Sun, 30 Jan 2011 01:44:06 +0200
Cc: Christian Zoffoli <czoffoli@xxxxxxxxxxx>, Jia Rao <rickenrao@xxxxxxxxx>, xen-users@xxxxxxxxxxxxxxxxxxx
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On Sun, Jan 30, 2011 at 10:41:23AM +1100, James Harper wrote:
> > 
> > On Wed, Jan 26, 2011 at 11:38:52AM +0100, Christian Zoffoli wrote:
> > > Hi,
> > >
> > > if you want to push on performance the best one is:
> > >
> > > CLVM over iSCSI
> > >
> > 
> > And if you need snapshots, just over normal LVM over shared iSCSI LUN.
> > (in this case your management toolstack needs to take care of locking LVM
> > control).
> > 
> How sure are you of this? Every write to the original or the snapshot 
> involves a potential metadata update. If the original is mounted on one node 
> and the snapshot on another, I'm pretty sure that it would all go to crap 
> really really quickly.
> Have you actually tried this???

It's widely used.

Citrix XenServer (and XCP) do it like that, and also the 
Xen based VirtualIron did it like that.

-- Pasi

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