As in an automated task that prunes old content on a regular basis? This is possible with an addon. If you are a programmer then you can post in the Development Questions forum for help with this. Or post an Add-on Request and some one may be able to write this for you.
That's how I recommended someone to do this. Database backups work like a charm, and are darn easy. Here's another free tip in case you have your own server. If you want a full backup of the drive you have your OS and filesystem on, ideally you have those running on RAID 1 (mirrored). I assume that you, like a good sys admin, have extra disks of the same size lying around as a safety caution for when one of these disks would fail. The next time, after a system update or upgrade, pull one of the disks out, label it as "System backup", and replace it with one of the spare ones. Tada, instant system backup.