I want to use Ubuntu Server on a computer which I want to use for my backups. I would like to be able to add extra disk space if that would be required in the future. Basically, I like what the Drobo does, however, I don't like that it uses a proprietary file system. Which means that I totally depend on them if it breaks.
So I have looked into mdadm for RAID 5 + LVM. However, that will not use all disk space if new disk are larger than the old ones. (LVM for the snapshots) I think ZFS could do the trick, however, that is unsupported on Linux. BtrFS is a bit too young to trust my files to, it is my backup after all, I want stuff to be safe there.
Another reason for me to want an ubuntu machine instead of a NAS, is that I want to run other stuff on it as well, like Django, mythtv backend and mail server.
So what options do I have if I want my files to be stored in a redundant fashion, and to be able to take snapshots of these backups as well?
I'm still in the research phase, so I am open for suggestions. :)