[ABMX]

I've seen pen drives naturally degrade over time, or even get shorted from an unexpected powerspike. I've also had CD/DVDs that stopped working years later.

I've seen people setup their computers with 2 drives in RAID1 and will pull and replace one of the drives regularly and put the hard drive in an anti-static bag and store it.

I know some tech support companies out there offer offsite backup with their services that do incremental backups and keep it syncronized accross multiple systems in multiple datacenters.

Can always keep a couple spare hard drives dedicated to running backups, a dedicated backup server/computer that your other systems just connect to each night to make regular backups.

There are these "Gold" DVD/CDs out there that supposedly are rated for like 100 years. I've never worked with them before, but doesn't hurt to mention them.