Hi all, I need some help finding a suitable application to run backups with. I'm using Ubuntu Server 10.04 LTS x64 as the operating system on my 8TB NAS (soon to be 12.04 at the end of the year). The machine runs beautifully serving all sorts of clients via SSHF and Samba. I have 16TB worth of drives (2x1TB/4x2TB/2x3TB) and as you can tell every primary running drive has a backup drive. Data stored doesn't change a whole lot and isn't highly important but if a drive were to die I'd just like to replace the primary with the backup and buy another drive to become the new backup.

Essentially I need a program that can clone all data sort of like a sync, removing deleted/moved files on the backup drive when changed on the primary and dealing with 1 file at a time (so if the primary were to give in whilst running a backup, files yet to be replaced will remain on the backup drive).

My current backup plan works but has a huge vulnerability. I delete all data on the backup drive and fresh copy all data from the primary. So if the primary were to die I'd have lost all non-duplicated data. Also, it takes longer due to copying all data rather than what is needed.

So to recap, I need a program that can:
- Copy data from one drive to another
- Skip already existing duplicate data
- Replace updated/changed files
- Delete moved/deleted data (otherwise the backup drive will run out of space)

Thanks heaps. If you need more info just ask.