If you have a few hundred gigs or so of data to back up, you might consider burning them to disc. 4-8gigs per burn may take a while, but i've had a drive fail and recovered most of my files because i burned them and kept them safe, in fact my burned discs still work just fine.

I've had a WD drive die too, but it was with in its 3 year warranty and got it replaced for free.

uh instead of burning hundreds of disks, how about 2 backup drives?

Multiple reasons.

1) No Moving parts. No moving parts means no maintenance.
2) No single fault point. Specifically if one disc is dead (for some reason), the rest won't necessarily share the same fate.
3) Cheap. Burnable DVD's are about 25 cents per, which is comparable to a hard drive (at least when i was considering it and did the math back a while ago)
4) No reliance on a electronic board. I've had a hard drive fail and had to have the drive replaced because of it losing all my data. Had timing been a little better the board replacement could have fixed that, but it was under warrenty, so...
5) Modular Chunks. You will put related games into the same DVD, and because of space limitations you mark on the disc what's on it, either in general or 6 items it covers before the disc runs out of top writing area.

Now I'm not saying you should backup on hundreds of discs, that's probably not worth it. But up to 50? Getting a CD case for them isn't that hard. In Korea i know solders who put all their games and discs in a large sleeve case. PS2, PS1, XB360, music, movies, etc. (This was back in 2005)

Actually, optical discs (that includes CDs, DVDs, Blurays etc.) are all prone to decay:
http://www.makeuseof.com/tag/cds-truth-cddvd-longevity-mold-rot/
Also scratching and random CRC errors.
They are NOT a recommended mode of backup.

True, but all my DVD's and backups are fine. Naturally i keep them in a dry cool environment where they won't get scratched up. I'm also reminded that the longevity of a disc is partially based on it's formula, which changes out so often that the Smithsonian had a test which puts them through about 20 years of wear and ones that fail are rejected.

I agree relying on discs is not the best thing to do, but really none of the backup methods are really that good.

Yeah, I agree. Like I said on my first post, you really need to have at least three backups at three different locations if something is mission critical. And even then nothing is guaranteed.

That mostly depends on how portable the device has to be. When you plan to carry around the drive often (maybe to store the backup in a different location) buy a 2.5" drive as it's smaller and usually does not need an external AC adapter. If the drive mostly stays in the same place buy a 3.5" drive as you get more storage capacity for the money. I have several external WD drives, from 120 GB up to 5 TB, both 2.5" and 3.5", and I've never had a problem so far. But if you are concerned about reliability just use 2 of them, depending on your backup strategy either alternating or in a RAID.

I've had drive heads go ca-click before. You can send the drive to get fixed (maybe) and data recovered (maybe) but it's very expensive. But maintenance goes more towards the drive's board.

I'd only check discs I actually am curious might have issues. A recent drive that was failing I checked and it takes something like 48 hours because of how much issues it was having so... Just because it takes 3 minutes for a quick check while the drive is acting okay, later it won't be so easy. Not to mention if the files are heavily fragmented...

The board. If you turn the raw hard drive over you'll see the electronics board, which is directly connected to where the power/data lines are. Maybe it's more hidden with some drives, almost all drives have exposed boards. Like this. I've had a drive with the board going bad, going back to #1 with maintenance. They can cost half the price of the whole hard drive, but cheaper than sending data to be recovered at something like $100 a gig... I investigated it a little, ended up losing 2 weeks of data that i really wanted to not lose but *shrugs*.

What do you mean? What maintenance am I supposed to do on the board? The plastic circuit board??

Why would a backup drive be fragmented? It is not used enough for that.

Are we talking about the same thing here? External backup harddisks stashed in a cupboard?

I prefer portable ones for the simple reason that I carry my backup with me wherever I go. To my mind, there's little point in keeping your backup alongside your computer. If your house burns down or is burgled you are most likely to lose both.

Carrying it around all the time is reckless, just deposit it at someone elses house, parents,relatives, friends

And how am I supposed to do my regular weekly backups if it's at someone else's house? And how is it reckless? I've been doing it for years without any problems.

It is reckless because HDs are sensitive to bumps. And you are supposed to do your weekly backups with the backup at home, obviously not with the ones you keep outside of your home to safeguard against fire and break in.