2T, that's a nightmare, what do you do with it?
Hehe, now that is a good question. There was an old saying that goes something like: "Give them the resources, and they will find a way to use them." More often than not, it is all too true. The biggest problem is that users tend to collect so much JUNK, that they can't find what they thought they stored there anyway.
However, as I am fairly sure Doug and others will agree, only 1 disk is not the way to go.
Well, that depends a lot on how you use the machine, but yes more than one, PHYSICAL, backup is generally a good idea. Of course, under normal circumstances, the backup for your backup is the original. However, when Murphy sticks his nose into the mix, all bets are off (sounds like he got you good).
It is always a good idea to have an emergency backup. Mine consists of a USB stick, where I store all of my own personal data, and a few other things that would likely be difficult to get elsewhere. You can always get the OS, and most programs, from other sources, but you can't get your own address book, or e-mail, from other sources.
FWIW, I don't recommend storing more than one copy of a backup (including incremental, and/or differential backups, if you do it that way) on a single backup media. If it goes bad, you have lost the works. It is also a good idea to store an emergency backup off site. 14 backups, on 14 disks, won't do you much good if they are all destroyed by fire (for instance).
One of the newest backup media, is the "cloud". That might sound like a good idea, but in most cases, it is way too slow for doing normal backups. You also run a higher risk that somebody will break into it, and do bad things with it. My personal view is that the "cloud" is useful for sales people who need immediate access to things like price lists, and order forms, when they are out of the office. It is not a good place to put backups, or even photos.