By whom? Again, this is more a question for OpenStack than us, since we are the layer under, not on top of it.

XOA is meant to be disposable. Config is pretty thin, all Xen objects are in memory only. In case of problem, just deploy a new one and import the config. Works well for people who even lost their physical hypervisors (thanks for backup being entirely self-contained, even a fresh XOA is able to restore backups made by an old lost XOA)