DB backups are made in realtime to a backup server, there a dump is created every 12 hours, compressed awaiting download or rsync.

A small home server connects once a day to the backup DB to sync everything and uses rsync to download modified or new files.
These modified files are kept in a directory so I've still the original installation, modified files of the last half year / one month / 1 up to 7 days in case I need them.

In a worst case backups are 12 hours old.

I use the mod that creates a backup once a day, and I transfer those on to the HD every few days
I do have a few older CD's with a DB on them, but they are pretty old.