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Day: August 14, 2010

Broken Time Machine

This is not good.

Danielle’s computer has been failing to back up properly to an AirPort-connected Time Machine volume, so with her volunteering at the 3-Day this weekend I figured I’d spend some time getting to the bottom of why.

First I thought the issue might be the questionable USB enclosure that the backup hard drive was in, so I swapped to another. No luck. Then I figured maybe the backup volume was corrupt, so I wiped that, but that didn’t help either; the backup still wouldn’t run. Next I thought that perhaps the local drive might be having issues, so I ran the Verify Disk function in Disk Utility, which promptly informed me that the volume was so damaged that I’d have to boot some install media and do an offline test. I did this, started the check, and received the message shown above informing me that the volume is so corrupt that it cannot be repaired. It will now not boot, sitting only at the Apple logo / spinning progress indicator screen.

This is not good.

Now I will have to back up all the accessible data by hand, and hopefully I’ll be able to get all of her music, documents, and photos along with config files needed to restore them. I’m hoping that this can be accomplished by hanging an FireWire disk off of the machine, installing OS X there, using Migration Assistant to pull data over, wipe (and test) the main drive, reinstall the OS there, then again migrate all data from the FW drive.

While it’s difficult to say what caused this, I strongly suspect it’s related to an alarm clock application that she’s been using for a while. This application will wake a Mac from sleep and sound an alarm. As her machine is a Macbook, which is not designed to run while closed (since they dissipate heat through the keyboard area), a program waking the machine from sleep while the machine is closed results in the machine immediately putting itself back to sleep. This would repeat over and over until the alarm was canceled or timed out. With this app in use for the last year or so, odds are good that this super-fast wake/sleep cycle has happened hundreds or thousands of times.

Due to the extremely complex things that happen when a machine is sleeping and waking, I strongly suspect that some things didn’t get read from or written to disk quite properly during the wake/sleep cycle and the disk became quite corrupt. Then, the software designed to repair this corruption couldn’t deal with how bad things were, left the disk in a less-usable state, and the machine is then left where it now is: failing to boot.

UPDATE: This corrupt disk problem was fixed as I hoped it would be above, with the external FW disk. Unfortunately Time Machine still isn’t working. Time to keep digging…

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