http://simplygenius.com/geekblog/2008/01/27/mounting-xen-domu-lvm-disk-in-dom0/ Matt Conway's blog - Keeping track of all my bits Thu, 04 Dec 2008 20:50:23 +0000 http://wordpress.org/?v=2.2 http://simplygenius.com/geekblog/2008/01/27/mounting-xen-domu-lvm-disk-in-dom0/#comment-165 Frank Fischer Sun, 08 Jun 2008 21:31:03 +0000 http://simplygenius.com/geekblog/2008/01/27/mounting-xen-domu-lvm-disk-in-dom0/#comment-165 As I understand you, you take the snapshot from dom0, right? Why did you do this? As far as I understand the inner yards of LVM, this way it is not guaranteed that the snapshotted FS is in a consistent state. The domU FS doesn't know that the snapshot is taken. If you have taken the snapshot from within domU, the fs is aware of the snapshot and brings everthing into a consistent state. That's the reason why most of the backup procedurece concerning xen found in the web are broken - they pause the domU and then they snapshot the LVM from within dom0. TO have a complete and guaranteed working backup you need the memory image of the paused domU too. Not so if you snapshot from within domU. As I understand you, you take the snapshot from dom0, right? Why did you do this? As far as I understand the inner yards of LVM, this way it is not guaranteed that the snapshotted FS is in a consistent state. The domU FS doesn’t know that the snapshot is taken. If you have taken the snapshot from within domU, the fs is aware of the snapshot and brings everthing into a consistent state.
That’s the reason why most of the backup procedurece concerning xen found in the web are broken - they pause the domU and then they snapshot the LVM from within dom0. TO have a complete and guaranteed working backup you need the memory image of the paused domU too. Not so if you snapshot from within domU.

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