Re: I've rarely used Xen
Snapshots at a hypervisor level have never been a backup mechanism.
Now snapshot-aware backups are of course useful, but that's not the same thing.
How about home-rolled Perl scripts that kick off a snapshot to freeze all of the data in the middle of the night, and then extract the frozen copies of the drives to a staging JBOD before removing the snapshot and committing to tape?
Worked a treat for years in a variety of guises, covering VMware GSX, VMware Server 1, XenServer 5.5 and finally ESXi 4.1. Especially when no money was forthcoming for server software, so VCB wasn't an option. Much happier to be using Veeam these days (although I've just had an email saying they're putting their prices up...)