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RE: [Xen-users] Backup; mount domU FS RO?

To: <Xen-users@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-users] Backup; mount domU FS RO?
From: "Daniel Goertzen" <daniel.goertzen@xxxxxxxxxxx>
Date: Mon, 19 Dec 2005 13:18:00 -0600
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 On Mon, Dec 19, 2005 at 08:04:50AM +0100, als@xxxxxxxxxxxxxxx wrote:
> A better approach is to use LVM and snapshots. Use LVM logical volumes 
> as "disks" for your DomU (if you aren't already doing this), create 
> snapshots for your backups, mount the snapshots and backup _those_.
> I'm currently using this to backup our production DomU systems from 
> the Dom0 and it works very well.

How do you assure that domU's filesystem is in a consistent state when the
snapshot is being taken in dom0?
Also, which distro+kernel do you use?


You won't know, but I bet it works most of the time.  While taking a
snapshot the LVM system will lock the VFS to assure consistency.  In the
above scenario the dom0 has no way of locking the domU's VFS, therefore
consistency is NOT assured.  The LVM user above should be creating the
snapshot from the same domU that has that logical volume mounted... At this
point you're probably better off with another solution.


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