A new optical disk technology offers a fundamental new capability -- which is storing offline archives in a format with a shelf life of many decades (or even centuries). The key is in the pits: unlike commonly available dye-based CD-R and DVD-R media, the Millenniata writer actually laser etches physical pits into the writable layer of its "M-Disc" DVD-ROMs. Because the pits are physical structures, like the pits on pressed media, they have the same kind of shelf-life -- but in a way that is economical for low-copy archives. The niche here is for digital archives of "time capsule" data: family photographs, historical records, original manuscripts, video footage and masters, and so on. Perhaps more remarkably, the drives and disks, are affordable enough for the target applications and available commercially right now.

A good backup system can help you recover from a lot of different kinds of situations: a botched upgrade (requiring re-installation), a hard drive crash, or even thumb-fingered users deleting the wrong file. In practice, though I've experienced all of these, it's the last sort of problem that causes me the most pain. Sometimes you just wish you could go back a few days in time and grab that file. What you want is something like the Internet Archive's "Wayback Machine", but for your own system. Here's how to set one up using the rsnapshot package (included in the Debian and Ubuntu distributions).