What do you think is the best method for backing up xen guests when LVM storage is used? While snapshots are helpful, they dont work in a clustered environment (aka, when clvm is used). The only option i can think if is dd, but thats pretty slow and inefficient. AFAIK, a lvm would have to be copied with dd to a set of temp files, then tar'ed up from there and vice versa.
DD also doesn't work in a clustered environment.
Your best bet would be a SAN device (or Linux server) that locally has LVM partitions, exports them as iSCSI partitions and you do the snapshots locally.
You can also use DRDB to replicate the drives to a standby machine and do the backups from there to lower the impact on the nodes themselves.
That said, you can also just run Rsync within the nodes, it's pretty easy and compatible to everything out there.