Time Machine backups corrupt or external hard drive failure?

Question

My goal today was to upgrade my MacBook Pro's HD, and to restore my system from my latest Time Machine backup which resides on an external hard drive. I installed the new hard drive, formatted it as Mac OS Extended (Journaled), and selected Restore System From Backup from Utilities. The system restore was five minutes form finishing when I received an error that the system restore could not be completed, and that I should restart my machine and try again. I did as instructed, but once the system restore process began, the screen went gray, and I was told that the Snow Leopard install could not be completed.
Before beginning the process a third time, I ran Disk Utility from the Snow Leopard install disc and attempted to verify and repair the external (Time Machine) hard drive. The Time Machine hard drive could not be verified, nor could it be repaired. I popped in the old hard drive into my MacBook Pro, booted Snow Leopard, and ran Disk Utility, and tried again repairing the Time Machine hard drive. Here is the log of the error I received:
2010-12-29 21:14:30 -0800: Verify and Repair volume “Time Machine”
2010-12-29 21:14:30 -0800: Starting repair tool:
2010-12-29 21:14:31 -0800: Checking Journaled HFS Plus volume.
2010-12-29 21:14:31 -0800: Checking extents overflow file.
2010-12-29 21:14:31 -0800: Checking catalog file.
2010-12-29 21:20:22 -0800: Invalid node structure
2010-12-29 21:20:22 -0800: The volume Time Machine could not be verified completely.
2010-12-29 21:20:22 -0800: Volume repair complete.
2010-12-29 21:20:22 -0800: Updating boot support partitions for the volume as required.
2010-12-29 21:20:22 -0800: Error: Disk Utility can’t repair this disk. Back up as many of your files as possible, reformat the disk, and restore your backed-up files.
2010-12-29 21:20:22 -0800:
2010-12-29 21:20:22 -0800: Disk Utility stopped repairing “Time Machine”: Disk Utility can’t repair this disk. Back up as many of your files as possible, reformat the disk, and restore your backed-up files.
Do these errors indicate that my Time Machine backups located in the Backups.backupdb are corrupt, or is the external hard drive corrupt and failing?
The Time Machine backups are on a Maxtor OneTouch, and from what I've read, they're prone to an early demise. I've also recently noticed that my Time Machine backups started slowing. For example, I would plug in my external hard drive and if 1.3GB needed to be backed up, it would stall at 300 MB before jumping to 700 MB, stall again, then jump to 900 MB. That could be a sign of a failing hard drive, correct? If the external hard drive is failing, I can purchase a new eternal hard drive then copy the Backups.backupdb to the new hard drive, correct?
However, if Backups.backupdb is corrupt, then from what I understand, I would have to start fresh. I would prefer to not start fresh unless there's no other option, as I would be losing almost three years worth of Time Machine backups.
Any guidance is appreciated. Thanks!

Answer 1

ali_baba7 wrote:
2010-12-29 21:20:22 -0800: Invalid node structure
2010-12-29 21:20:22 -0800: Error: Disk Utility can’t repair this disk. Back up as many of your files as possible, reformat the disk, and restore your backed-up files.
It's possible a heavy-duty 3rd-party utility such as +Disk Warrior+ can fix that. It's about $100, and there's no guarantee, but it's probably a good investment for the future.
Do these errors indicate that my Time Machine backups located in the Backups.backupdb are corrupt, or is the external hard drive corrupt and failing?
The structure of the file system is damaged.
That may have been caused by the disk beginning to fail, but there's no way to tell for sure until you erase and reformat the disk and try to use it.
I've also recently noticed that my Time Machine backups started slowing. For example, I would plug in my external hard drive and if 1.3GB needed to be backed up, it would stall at 300 MB before jumping to 700 MB, stall again, then jump to 900 MB. That could be a sign of a failing hard drive, correct?
It could, but it could also be whatever's wrong with the file structure.
If the external hard drive is failing, I can purchase a new eternal hard drive then copy the Backups.backupdb to the new hard drive, correct?
No. You can't copy corrupted backups. They're all linked together, like a database, so if anything's damaged, the whole set is suspect, and can't be copied.
There are a couple of options:
If the disk is physically ok, and the directory damage was recent, you might be able to restore from an earlier backup. But since you noticed problems some time ago, the damage may not be recent.
Or, you might be able to get up and running by just installing OSX from your SL Install disk (and the 10.6.5 "combo" update). You'll be missing whatever wasn't restored in that last 5 minutes or so. Things are restored in the same order they're listed by the Finder, so it will be the last things in the last user account. You should be able to figure out where it stopped, check or delete the very last file (likely incomplete) and selectively restore as many of the remaining things as you can, via the "Star Wars" display.
Just to make things more difficult, if the disk is failing, the more you use it, the more likely it is to get worse or fail completely.
So your safest bet may be to install OSX, then download and install the 10.6.5 "combo" update. Info and download available at: http://support.apple.com/kb/DL1324 Be sure to do a +Repair Permissions+ via Disk Utility (in your Applications/Utilities folder) afterwards. Then recover what you can.