With the recent announcement of Apple’s Time Capsule product, and the encouragement from Steve to his users to backup their stuff, I thought I’d take a moment to clarify a distinction between what backup means and why you might (in some cases) be archiving rather than “backing up”.
A backup is an extra copy of something currently on your computer, stored in another place. It’s purpose is so that if one of those locations fails (the source or the backup location), you still have one copy and you haven’t lost anything.
Archiving, on the other hand, is the storage of your data on another device (or burned media, etc.) for the purposes of keeping it around for a while. An example of this would be if you have a bunch of large files for a project you’ve been working on on your laptop, and now that you’re done with that project, you move those files off to your network attached hard drive, to free up the space on your laptop.
I’ve often heard the latter referred to as “backing up”, but of course it isn’t, because your data is still only in one place, and you will lose it if that network drive fails. What you really want is to be sure that for all your data (both your “archived” data and the stuff you use every day) to be backed up.
On a related note, while the Time Capsule is a cool device, I think it would have been good if they included RAID capability. That way if the HD in the capsule dies, you haven’t lost everything. This would especially affect people who are archiving stuff to the network drive and thinking of that as their “backup”, because then their data would be gone.
If you’re looking for network storage for the purposes of backup and/or archival, I recommend a cheap Linux box that you can load up pairs of hard drives into as needed, using RAID 1 or 5 to provide redundancy. This way, if a drive fails, you just throw in a new one and let it resync, and you haven’t lost any data. Fry’s frequently has sales on hard drives; these days you can often find 500GB for under $100. I’d choose Linux’s software RAID support too, rather than going with a RAID card or built-in motherboard RAID support; I’ve seen people get stuck when their decade old RAID card fails and they can’t find a replacement because they don’t make them anymore.
If you do the RAID thing, you’re pretty safe from drive failures, but for data you really care about, you should probably still have a separate backup copy, preferably off-site, to account for things like theft, fire, or other damage that might affect your local storage.