Saw this rsnapshot error this morning on a couple new Xen domUs that I created last week:

[08/Mar/2010:08:12:53] /usr/bin/rsnapshot hourly: ERROR: /usr/bin/rsync returned 255 while processing root@foo.bar:/
[08/Mar/2010:08:12:53] touch /backups/hourly.0/
[08/Mar/2010:08:12:53] rm -f /var/run/rsnapshot.pid
[08/Mar/2010:08:12:53] /usr/bin/rsnapshot hourly: ERROR: /usr/bin/rsnapshot hourly: completed, but with some errors