[CentOS] Backing Up A Xen Guest

John Summerfield debian at herakles.homelinux.org
Tue Mar 27 00:48:22 UTC 2007


Graham Jenkins wrote:
> Here's the problem. We perform full tar backups of our CentOS 4/5
> machines in real-time at regular intervals. And when a disaster happens,
> we are able to restore those backups onto virgin filesystems, make
> the /dev/null, /dev/zero and /dev/console devices .. and boot the
> machine.
> 
> This has worked well on standalone systems, and also on Xen 3.0.3 guests
> on CentOS 4.4 machines, where each guest filesystem resides on regular
> (Xen-host) real filesystem.
> 
> But there's no way we've been able to make it work for CentOS 5 Beta
> guests on CentOS 5 Beta Xen hosts, where each guest disk resides in a
> file.
> 
> The strategy goes something like:
> 
>       * losetup -o 32256 /dev/loop0 /XenGuests/Guest1
>       * mkfs -t ext3 /dev/loop0
>       * mount -t ext3 /dev/loop0 /mnt
>       * cd /mnt && tar xjpf /tmp/Guest1.tbz
>       * for i in console null zero; do /sbin/MAKEDEV -d /mnt -x $i; done
>       * cd /tmp; umount /srv/vm1; losetup -d /dev/loop0
>       * xm create -c Guest1
> 
> And it always gets most of the way through .. then the guest dies.
What does "most of the way through" mean?

Do those files have partition tables?

Why not attach those volumes ro to another guest?



-- 

Cheers
John

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