Apple TV repair

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Revision as of 09:21, 27 October 2011 by Shawn (talk | contribs) (→‎New hard drive: rebuilding gpt)
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Backup

I wish I had a backup of my drive before the Apple TV went screwy, but I made a backup of the screwy state anyway. Here's how:

I unplugged the device, then I removed the hard drive. I skipped the hair-dryer step, which was a mistake. iFixit has guides for disassembling the machine: http://www.ifixit.com/Device/Apple_TV_1st_Generation

(Before I attached the drive, I should have turned off Spotlight, so it wouldn't add search folders to two of the volumes).

I attached the drive, via USB <> PATA adapter, to my Mac. I unmounted the volumes on the drives using Disk Utility, which I kept open so that I could repeatedly unmount the drives easily while I worked.

I used gpt to view a snapshot of the partitions as they were. But first I found the name of the disk from Disk Utility by clicking on the drive and getting "Information." Your disk may be in a different slot of the /dev/disk# numbering order:

 gpt show /dev/disk1

Then I used dd to copy the entire drive as an image on my hard drive—make sure you have enough room, the ATV drive is at least 40GB. I put it in my Temp folder which I ordered Time Machine to ignore, so it doesn't bother backing up so huge a file.

sudo dd if=/dev/disk1 bs=1m of=~/Temp/appletv-orig.dd

You can press control-T during the execution of dd to see the progress. It took me about two hours to copy this way.

to be continued

New hard drive

I've tried many different methods to copy what's on the old drive to the new drive. At the very least, supposedly, I need the partitions, with data in the recovery partition copied exactly. With that, "Factory Restore" should put everything back in order.

I've tried online methods:

http://www.engadget.com/2007/03/23/how-to-upgrade-the-drive-in-your-apple-tv/3 . This method balked at the re-addition of the fourth partition after removing it.

Using a G5

Next to try: http://guides.macrumors.com/Apple_TV_250GB_Hard_Drive_Upgrade . I should try it on my G5.

Rebuilding GPT

  • Use gpt show on the original disk to see the partition table's exact measurements.
  • Use dd to copy from image, made with dd, of complete, original drive.
  • Use gpt remove to remove partitions 1-4 from the partition table
  • Use gpt add to replace partitions 1-3 with exact copies of the original partition measurements.
  • Use gpt show to determine the leftover space for partition 4.
  • Use gpt add to add a partition 4 that fills the rest of the space.
  • Use Disk Utility to repair the 4th partition, Media. It will see that the Volume Header's size (old size) doesn't match the partition table size (new size).
  • Remove .Spotlight-V100 from Media and OSBoot if they're there. Maybe single-user mode would be best so that automatic interlopers like Spotlight don't mess with our disks.

References

http://www.engadget.com/2007/03/23/how-to-upgrade-the-drive-in-your-apple-tv/