I'm currently using rsnapshot to backup a server farm where NFS is used heavily. Unfortunately, the current setup has us backing up the same files multiple times due to the NFS mounts.
For example, /etc/rsnapshot.conf has this:
backup backupuser@machine1:/local_directory/ machine1 backup backupuser@machine2:/exported_directory/ machine2
Now, machine1 has /local_directory/exported_directory mounted -- so I end up with backups of both machine1/local_directory/exported_directory AND machine2/exported_directory.
While I could work around this by either mounting things differently on the clients or by manually excluding the directories, I'd rather find a cleaner approach (which is probably a rsnapshot or rsync option).