[CentOS] Backing Up A Xen Guest

Sat Mar 24 07:06:33 UTC 2007
Graham Jenkins <graham at vpac.org>

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

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

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.

Ideas anyone .. please?

Graham Jenkins <graham at vpac.org>