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10.5: Beware using Time Machine with a failing disk System 10.5
I noticed some strange log messages and beachball hangs recently while using my MacBook Pro. The log message read MaBi kernel[0]: disk0s2: 0xe0030005 (UNDEFINED). I came to the conclusion that the internal disk was failing (see this blog post and associated comments for some discussion on the error message).

I thought the logical course of action was to attach my Time Machine backup disk, do one last backup, then get the drive replaced and do a restore. It turns out this was not a good idea, and it resulted in the wholesale trashing of the Time Machine backup. Only because I caught the failure early enough, when not much was lost (and noticed what Time Machine was doing), was I able still to take a "normal" rsync-style backup from which to restore from tomorrow when the replacement arrives.

I don't profess to have investigated the matter thoroughly enough to be certain. However, what appears to happen is that Time Machine attempts to run a backup which terminates due to an I/O error like this: But, bizarrely, Time Machine does not post an alert to the logged in user: the error above never even gets seen unless you happen to look in Console.app. Worse, it looks as if Time Machine itself actually thinks that the backup completed successfully. Any files that were not yet copied, including any later files that might have been fine, Time Machine seems to assume they have "gone away."

When I went to look in what was left of my Time Machine backup, I found my whole Desktop was present and correct, but only a small portion of my Pictures library was there: presumably it only contained those files copied before the error caused the backup to stop.

I then thought moving the bad files somewhere that doesn't get backed up by Time Machine would make it so that I could at least complete a full backup, but that only made things worse. This time, because the previous backup was missing so many files, Time Machine decided it needed a full 40 GB extra space, and reclaimed that by removing some of the old backups. Of course, what then happened was that the backup failed on a different bad file, but by this time so much had been removed from my backup that it was virtually worthless. It was at this point I decided to quickly take the rsync backup option.

The moral is to be very careful using Time Machine if you have a questionable internal drive. And if you do, best thing to do is to turn off Time Machine's automatic backups and find some other way of preserving any recently-changed files if you need them.

I'm going to file a bug with Apple, as I think Time Machine should provide better feedback. But perhaps this is something others in a similar position should be careful of. Hopefully this is something that'll be fixed in 10.5.2.
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10.5: Beware using Time Machine with a failing disk
Authored by: rmillavec on Feb 06, '08 09:28:26AM

I have seen this issue with the hard disk reporting undefined errors in the console. This almost always happens with Macbooks. Usually the drive does not need to be replaced.

If you have a working backup then you may be able to get away with repartitioning the disk and reinstalling the os. Migrate data back using the migration assistant. After doing this the undefined errors almost always go away.



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BEWARE: Your drive is failing!
Authored by: a1291762 on Feb 07, '08 03:27:57PM

Your symptoms indicate the internal drive is failing. Be very wary of trusting it!

Hard disks come with a certain amount of spare space. When a physical defect is detected, the location is marked as bad and some of the spare space is used instead (so that the size of the disk does not mysteriously decrease).

The hard disk will not do this remapping when you try to read a bad location, only when you try to write to the bad location. Thus you cannot backup your data but you can format and re-install.

The problem is that a drive will start failing but with a re-install you'll think it's actually ok. Most of the time though the failures will accelerate and you'll quickly find yourself losing data if you're trusting that disk. When will this happen? Once the spare space has been used up you'll get unrecoverable problems. Do yourself a favor and buy a new disk before that happens.



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Beware od some MacBook hard drives
Authored by: wallybear on Feb 06, '08 11:07:11AM
Take a look to your hard drive specs: if your MacBook is about one year old or little more and your internal hard drive is a Seagate, there are good chances it's going to die very soon.
You can easily verify if your drive is one of those predestined:
- Launch System Profiler
- select Serial ATA in the left column; on the right one you'll get the specs of your hd

If your hd:
- is a Seagate 60/80Gb (model ST9xxxx)
- has firmware 7.01

you can be quite sure it will fail really soon. I had many returns from my customers of this particular hd models. Those drives dig scratches on the first racks of platters, and are unrecoverable.

You can also find more information about the problem here: http://www.retrodata.co.uk/notice_apple_seagate_drives.php

In case you have one of those drives, back up frequently and try to get it replaced under warranty (as it is a defective product, it could be possible also if your warranty is expired).





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Beware od some MacBook hard drives
Authored by: denty on Feb 07, '08 02:44:10AM

Thanks. I did ckeck this as one of my friend's MacBook drives died recently. It turns out my drive was a Toshiba. I'd dropped my MacBook Pro a few times, so I decided it was perhaps my own fault.

Apple's bug reference is # 5712347, though it is still in an 'open' state.

I got the replacement drive and, in the end, only lost two personal files (though I had to do a full OS re-install, as many of the /Applications bundles had been trashed).



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Beware od some MacBook hard drives
Authored by: denty on Feb 09, '08 01:08:56AM

Just a further note to say that Apple have identified this as a duplicate of bug # 5673197. They don't provide any further information, but at least it points to the fact they are actively looking into the matter.



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10.5: Beware using Time Machine with a failing disk
Authored by: rwikoff on Feb 06, '08 09:54:39PM

I had a similar problem and also found that Time Machined fails to backup files that were not backed up by a prior failure. However the backups prior to the failure should still be complete.



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10.5: Beware using Time Machine with a failing disk
Authored by: homepup on Feb 25, '08 07:34:49PM

Totally agree with this one. I lost a hard drive a couple of weeks ago, received a replacement and restored via my Time Machine backup. Then noticed a couple of days later that half my iTunes library was missing. Upon digging deeper, realized that my hard drive had been failing for a couple of weeks without any warning. You could actually see the files disappearing by going 'back and forth in time' via Time Machine.

Now my dilemma is do I go to a backup that's a couple of weeks old and lose any changed files over the past couple of weeks, or just wait until I come across more missing files and manually dig for them in Time Machine.



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