Mondo Rescue backs up your file system to CD, tape, NFS (archives stored remotely) or ISO's (archives stored locally). Mondo uses afio as the backup engine; afio is a well-respected replacement for tar. In the event of catastrophic data loss, you may restore some or all of your system, even if your hard drives are now blank. Mondo Rescue can do a lot of other cool things:
You can use Mondo to clone an installation of Linux. Just backup the crucial stuff and exclude /home, /var/log, etc.
You can backup a non-RAID file system and restore it as RAID including the root partition (if your kernel supports that).
You can backup a system running on one format and restore as another format.
You can restructure your partitions, e.g. shrink/enlarge, reassign devices, add hard drives, etc, before you partition and format your drives. Mondo will restore your data and amend /etc/lilo.conf and /etc/fstab accordingly.
You can backup Linux/Windows systems, including the boot sectors. Mondo will make everything right at restore-time. (However, do run "Scandisk" when you first boot into Windows, just in case.)
You can use your Mondo backup CD to verify the integrity of your computer.
Mondo's principal virtue is that it protects you from the problems that can arise when you reinstall completely from scratch. If you want to wipe and restore your system every year just as a matter of 'good practice', Mondo is not for you. However, if you want to get up and running again in a hurry after someone breaks into your computer and wipes it (or if you accidentally wipe it yourself) then Mondo is definitely for you. It will permit you to roll back to a known-good installation in a very short period of time, sometimes as little as twenty minutes. Even if you backup large amounts of data to tape daily and do not want to add yet another backup regime, please consider backing up the core filesystem (i.e. everything but the directories containing your huge database and your prizewinning novel) every month or so, just in case. You will be glad you did.
What is Mondo not?
Mondo is not an everyday backup program. It is not designed to replace tar, afio, kbackup, etc. Mondo is designed to make it possible to recover from scratch if necessary. Tar and afio offer a quick, convenient way to backup small sets of files, sometimes to removable media.