Given the main idea of this article I am interrested to know is there a standard deffinition or classification of levels of backups?
If not, I propose one.... something to this effect.
Level 0 - No backup, file is stored locally on single machine on single hard drive
Level 1 - File is stored on single machine with RAID
Level 2 - File is stored in original location as well as on single backup drive or thumbdrive (not offsite)
Level 3 - File is stored in its original location, a second storage device such as portable Hard drive, and then a third copy off site
No backup solution can be called a true backup if it does not include an offsite backup and the best offsite backup is one some distance away from where you store the originals. If you leave a copy of the files at your nighbors house and your house burns down then you're okay, but if a tornado blows both your hosues down then your screwed. Get a safe deposite box at the bank or something... Right now I have the original files on my PC, a second copy on an external drive I keep in a fireproof lockbox I update once a month or so, and then a third copy on another external drive I carry from work to home with me from time to time. There is always a possibility that one day when I bring my drive home from work and have all the drives in the same location disaster could strike.
You really need to ask yourself, "how much is my data worth."