Recovering data after destroying the Mac OS X partition table

I’m not a religious man but every once in a while I do something stupid and find myself hoping for some divine intervention. Yesterday, I excelled in my stupidity with what was probably the single most careless thing that I have ever done in my entire computing life, accidentally re-initialising my external hard disk (containing, amongst other things, my iTunes library and irreplaceable digital photos of my children) and the backup disk.

In a mild state of panic, I called my friend Alex who gave me two excellent pieces of advice:

  • Do nothing with the corrupted disks. Sit tight. Calm down. Wait and see what turns up from researching similar scenarios on the ‘net.
  • Submit a post to some of the Mac forums (Mac OS X Hints, Apple Discussions, Mac Geekery) and see if anyone can recommend a suitable course of action.

Thank you Alex.

And thank you Stanley Horwitz, debaser626, Tom Larkin and Joe VanZandt for coming back to me with recommendations almost straightaway. Almost everyone suggested running a tool from Prosoft Engineering called Data Rescue II.

In addition to its primary role of recovering lost data on hard disks, this $99 utility (a small price in comparision to professional data recovery fees) has two especially important features: it is non-destructive as all restoration has to be to another volume; and it can be run in demo mode first to check that data is recoverable before having to be registered.

A quick scan turned up no recoverable files but a thorough scan was more useful. After a few hours reading 6 billion disk blocks and another couple analysing the data, it found my files. Unfortunately the progress bar gives no indication as to how many files might be recoverable whilst the scan is taking place, presumably because files may be spread across many disk blocks but it found my files!

The recovered files were marked as orphans, CBR (whatever that is) and then a whole load of them actually had their original file names and other metadata. After successfully recovering a single file, I bought a license and set about recovering the entire contents of the disk to another volume. Unfortunately it hung after failing to read one of the files but I repeated the operation (this time saving my scan results so that I can exit and relaunch the application if necessary) and successfully restored my digital photos. The relief is immense and I’m presently running a full restoration of the entire disk contents (I imagine that a large part of tomorrow will be spent working out which files I need, and which were actually deliberately deleted files recovered along with the lost data).

Other potentially useful tools, which I didn’t try but which might be useful to others, include:

  • GRC Spinrite – for proactive hard disk maintenance and recovery of data from failing hard disks (disk recovery – not partition recovery)
  • Alsoft DiskWarrior – for damaged directory structures (file system recovery – not partion recovery).
  • SubRosaSoft File Salvage – another partition recovery tool.

Note that I haven’t tried any of these tools myself – I’m simply alerting any poor soul who stumbles across this page to their existence.

I was lucky. Very lucky.

The moral of this story – don’t rely on a single backup that is overwritten nightly and permanently connected to your computer. I really must take more frequent DVD backups of crucial files and store a disk backup offsite.

I should know better.

4 thoughts on “Recovering data after destroying the Mac OS X partition table


  1. Please help me. I have purchased Data Rescue II and an external harddrive. I managed to format my new harddrive so that the Mac will acknowledge the drive.

    Data Rescue loads fine and when I chose which drive to scan, all the drives show up. But when I chose the working volume, it only shows the boot volume and my new external harddrive is not available. What am I doing wrong????


  2. I think I could copy & paste your first paragraph and use it myself! I did exactly the same thing, albeit Disk Util deciding to corrupt the whole two volume firewire disk when trying to erase the first volume. Panic!
    5 minutes with google, your blog entry appears. I repeat your experiences, mostly to the letter…
    Your blog post saved me from a second major panic attack. Thanks!


  3. @Jennifer – I’m really sorry but I can’t help. Your best bet is to contact Prosoft (after all, you did purchase their software, so I’m sure they will provide some support).

    @Neil – glad to hear this was useful to you. I still shudder when I think back to that day or so of waiting to see if I could get the photos of the children back.

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