Been having some problems with my iMac upstairs. I'm pretty sure the hard drive is failing (again), although hopefully it's just bad sectors. But, with hard drive prices currently still in the stratosphere, I decided to try one more last trick to see if I can save myself some money. That is, the old Windows trick: fdisk, format, reinstall. Or, well, the Mac Equivalent - Disk Utility, reinstall.
About a year ago, a bought a Drobo. I've been meaning to write a review of the Drobo and maybe now I will (the short of it is, I had some growing pains with it, but now that I've figured out its quirks, it seems to work well). One of the reasons I bought the Drobo as to use a shared Time Machine backup store for all the Macs in the house.
So, I thought, in addition to trying to save my Mac, now would be a great time to test my fancy Time Machine backup system. And, unfortunately, since Time Machine really isn't meant to work with unsupported network volumes, it does require some gymnastics to get it to work. Even worse, it isn't a very well documented procedure. But, ultimately, I was able to figure it out; I'll post what I did hoping that maybe it will save someone some time and headache.
First step is to format and reinstall as you normally would. If you are on/installing Lion, you may be presented with an option to reinstall from a backup as part of the install process. Don't do this. Reinstall Lion as if you were performing a fresh install.
When the installation is complete and you get to the Lion post-install setup screens, you will (eventually) reach a screen asking you to create a user account. Create your original user account (same username) as in your backup.
Once you're out of setup, go to System Preferences, then Users. Create a new administrative level user (I called mine "foo"). Be sure this is an admin-level user.
Log out and log into the account you just created.
Turn on unsupported Time Machine volumes. Open up a Terminal window and enter:
defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1
Now, open up a finder window and navigate to your Drobo or other device and to whatever network share you have your Time Machine backups stored on. Mount it.
Now, inside the share, mount the .sparsebundle that is your restore image (it should be the machine name). If you open it, you should be able to see a folder called "Backups.backupdb" in it.
Next, fire up the Migration Assistant.
Select "From another Mac, PC, Time Machine backup, or other disk." Hit continue.
Select "From a Time Machine backup or other disk." Hit continue.
It may take a second, but, eventually, you should see a drive image and the name of your old hard drive (usually "Macintosh HD") appear. Click continue.
It may take awhile for it to parse the image. My backup image was about 350gb, and it took about 20 minutes to parse out all the information. Select what you do or don't want and click continue.
You should be presented with a dialog stating that a username on the system is the same as one in the backup. Select "Replace..." Click continue.
Wait. It will take awhile. It took about 5 hours for me to do a complete restore from a backup on the Drobo to my iMac.
And that's it. Once it finished and you reboot, your Mac should be just as it was during the last backup.