the easiest way would be to take a snapshot from xenserver itself and export it to template
this solution results in a file-based backup of a virtual machine, you can reimport such vm easily via xencenter, the only thing it requires is some kind of storage to write backups to (cifs/nfs/usb hdd and such..)
but keep in mind that it is slow, as you have to dump all data blocks that have been at least once written and not only currently used space
for example new vm with 20gb hdd and only 4gb used will most probably result in 4gb backup file, old vm which had some writes done, will hit 20gb easily even if it still uses only 4gb of space
http://www.andy-burton.co.uk/blog/in...ws-cifs-share/