When I worked at the Genius Bar I occasionally, usually around this time of year with all the electrical storm activity, would have a customer come in with the ultimate in data failure nightmares. They would have a backup on a 2nd hard drive and both it and their primary drive would be hosed from an electrical spike.

My scheme is to have a Time Machine backup, a secondary hard drive back up that is unplugged from the wall when not in use, and all my taxes and financial information archived every 3-6 months on DVD. For a while I even kept a second backup hard drive off site (bank safe box) in case of fire.
Always, always remove your backup drive from your house's AC lines if there is a storm going on. Power surges can make a multiple point of failure (2 drives) system into a one point of failure system (the outlet) instantly. If you rely on an internal hard drive, then unplug your computer during a storm. This, IMHO, is one of the best arguments for today's powerful portable computers. If I don't need my Mac Pro's power, I use my MacBook mostly because the couch is more comfortable than the desk chair. If I hear thunder, I knock the Mag Safe adapter off the machine. Then I move my data to the Mac Pro at my convenience where my backup scheme takes over.

I am unusually conscious of backing up. Lots of personal horror stories led up to this enlightenment. If Apple is offering a backup solution, it needs to "just work". The .Mac Backup program used to be the bane of my existance. it makes good backups, but it often requires arcane manual restoration of the data. The restore part of the product just pain sucked. Of course, the nature of my job meant that I never saw any customer's machines when they were working as designed.

Want to be truly data-safe? Keep multiple backups.

Want to confuse someone and possibly get a grin? Go to a random Genius Bar and tell the staff that everything is fine and they're doing a great job. Trust me, it's a rare experience for them.

You can also check out Multiply Premium, which launched today. It works on Mac/PC/Linux and offers a secure, remote archive for all photos and videos and the discussions around them.

You can learn more about Premium by visiting: http://multiply.com/premium.

Using just one backup is fraught with peril. But I am writing this on a machine with only the TimeMachine backup. I also use .mac sync and iDisk to keep important data safe; I figure that both my iMac and Power Book can't die at the same time. (But two weeks ago they did - TimeMachine saved me).
I intend to get SuperDuper! for extra insurance backups.

Ive not had any problems with my MacBook Pro Time Machine. However I have had horrible problems with Time Machine and G4 iMac's. Once big problem with Time Machine is that most of the time the logs don't really tell you why it choked and it's not working. Time Machine some times after failing will start mysteriously working.

Question: Are the errors related to Time Machine itself, or crappy backup drives with sketchy reliability? Has it even been looked at? Some model drives aren't worth touching with a ten foot pole. I'm not relieving Apple of any culpability, I'm just adding an additional variable to the equation.

I suppose I've been lucky. I've had no issues with both a Mac pro and a Mac Book pro running 10.5.3 backing up to a 1TB Time Capsule. Then again, if that combination doesn't work, Apple has serious QA issues.

That said, Time Machine is a new feature and will likely take some time to mature and work out minor issues. Also, even though Time Machine has worked flawlessly for me (including restoring data), I occasionally do still make backups of my critical data to other devices. At least twice a year, I also make backups to be stored off site in case of a disaster such as a fire, etc. Time Machine (like any backup software) may be better than nothing, but it's only piece of an overall backup strategy. Anyone who thinks otherwise is setting themselves up for a disappointment.

Seems to be working great for me, and I have restored from it. It is fairly new software, so there will be some bumps in the road, but you have to admit, it's an absolutely awesome backup technology.

I used to think Retrospect was good, but Time Machine blows it completely out of the water.

Try repairing the backup image. Disk Utility will repair the image, without mounting it (just open DU, drag and drop it from the backup drive to the left pane of DU), and that might fix your issue.

10.5 leopard time machine woes and how i got around them

I agree with the author; and that's why I don't even use Time Machine. It has some limitations that one would have thought Apple would have corrected. Plus, it seems that it's more bug-ridden than it should be. I use Superduper to back up (very, very easily) to an external hard drive; and I also use Jungle Disk for off-site back.

I have noticed this "bug" with the last update (occasional notice of failure to back up), but only if my backup is interrupted by computer's sleep.

Are there any issues using Time Machine with a laptop that has had FileVault enabled?

It would seem that anytime TM backs up a FV image, the entire image would have to be backed up, not just the few files that may have changed.

Same Time Machine error message on a 24-inch iMac.

Believe or not, there are many computer users who NEVER back up anything. I used to be one. Then I started backing up to CD's and occasionally DVD's. Then I bought a MAC and it frankly became much too simple a thing to back up everything. So, with Time Machine, I can at least say, I am moving forward. Where before . . . mostly left out to dry if my machine crashed and burned! I have, now, had one occasion to actually restore important data from the Time Machine and all I can say, is that it worked better than I expected. Thanks.

On the subject of file backup, sharing and storage ...

Online backup is becoming common these days. It is estimated that 70-75% of all PC's will be connected to online backup services with in the next decade.

Thousands of online backup companies exist, from one guy operating in his apartment to fortune 500 companies.

Choosing the best online backup company will be very confusing and difficult. One website I find very helpful in making a decision to pick an online backup company is:

http://www.BackupReview.info

This site lists more than 400 online backup companies in its directory and ranks the top 25 on a monthly basis.

Time Machine is for getting people who would not have performed backups to perform them. To that extent, it's probably worked.

That said, there are probably people out there who think they're "safe" because they're using Time Machine (rather than "safer.") Now that they've disturbed this hornet's nest, Apple needs to make it easier to take full backups off-line while continuing to back up, and they need to offer some sort of explicit validation operations.

SuperDuper! for backups against catastrophic hard drive failure.
TimeMachine for backups against user error.
Online, remote backup for the "really important" stuff.

I was very interested in this article. I have been using Time Machine to back up my Mac Pro for the past month. Today it started to back up and it said that it needed 412GB of disk space to back up my computer. All the data could not have changed on my computer since the previous backup the night before. Not very reliable....

If Time Machine actually tells you that the backup failed, could you still tell it's a bug?

A bug would be that Time Machine says "the backup failed", while it didn't.

Just my $0.02.

@ Chas
Sorry, but that's just wrong. Time Machine keeps archives and any file you change at all will have multiple copies of itself spanning back over time. As a result Time Machine will use more and more space over time. That's how it works, and the error is expected. Time machine is additive only so each backup will take progressively more disk space and eventually you'll run out. The prompt is designed to give you the opportunity to change your TM target disk so that you can keep your archive rather than simply losing to oldest stuff on a rolling basis.

The fact that you ran out of space indicates (if anything) that Time Machine is very reliably adding data to your drive. Given how the product works, I'd be more concerned if I never saw that error.
Read this from Apple:
http://docs.info.apple.com/article.html?path=Mac/10.5/en/15137.html

Time Machine is nice for enabling me to retrieve data that was on my computer for only a few hours, but I still back up with Super Duper every night, alternating between two Iomega portable drives that live in a small, fireproof safe in my home office. Financial data rides a CD to a safe deposit box quarterly. Found one major bug - MS Entourage "My Day" doesn't play nice with Time Machine. I disabled My Day and the problem went away.