Linux – Migration from Xen to KVM

Real "live" backups aren't exactly doable.

In theory, the best you can get - when using LVM - is a few seconds of "pause" time, which should be fine: a domU would need to - sync it's disks, pause/suspend, backup data, and resume.

However, there are a few "gotchas" with this approach (as opposed to just shutting down the machine) that need to be addressed.

The main issue is the consistency of the domU filesystem - have a look at thoughts-xen-filesystem-configuration-regard-backups for a more complete explanation.

"easiest to manage" is very relative - you just as well use file-based disk images and it would be ... simple - at least for a few guests.

Still, i would say option 2 is fine, though using LVM in the domU is completely optional. Of course, if you plan on expanding the LVs for the domUs later, having them use LVM will make things easier.

That i know of, there are no performance issues with having LVM in the domUs (it's not LVM inside LVM, its LVm inside Xen...)