I should have been more clear. The problem is that zbackup won't work for large data sets. For example, I used to use rdiff-backup for a samba filesystem at w

I should have been more clear. The problem is that zbackup won't work for large data sets. For example, I used to use rdiff-backup for a samba filesystem at work that had a few terabytes of files on it. The problem was that whenever someone would rename a directory all of the data in its subdirectories would have to be backed up again. Backup software that deduplicates solves this problem wonderfully, since it doesn't make a difference if the files have been moved or not. The problem with your approach is that I can't send several terabytes of data offsite every night. I could use the rsync trick I mentioned, but now I've got to store two copies of the data on the backup server.