The Secret of the Time Machine-Assisted Hard Drive Swap

Gizmodo published this article this morning.  I thought it was brilliant.

There's never been a better time to void the warranty on your MacBook and upgrade to one of those sweet 2.5" WD Scorpio 320GB drives. That was what made me throw caution to the wind and attempt a Time Machine-assisted swap. The good news is, it works as billed. You get a bit-for-bit transfer to the virgin drive with minimal fuss. The bad news is, if you don't use a little trick we discovered today, you probably won't get it to work at all.

I said "void the warranty" and I meant it. The process I went through today means it'll be harder for me to complain to Apple if things get weird, so be cautious! Given the experience I've had, I think HDDs will soon be given easy-access panels, like RAM has, because swapping a 2.5" SATA turns out to be straightforward, and the software, at least as far as Apple goes, is ready for novices.

The key here is that there's no preparation needed for the new drive. As long as you've backed up your old drive to an external disk using Time Machine, you can prepare for the grand opening. I won't bore you with gory details, except to say that I found a good bit of guidance from this dude's blog. 
The Process
Once you open up the system and swap out the drives, you can set the old drive aside, hopefully never to use it again. Assuming all went well, you restart the system and insert an OS X Leopard installation DVD. You won't need the OS installer on it, but you will need it to act as mediator between the Time Machine backup drive and the newly installed blank drive. Once it boots up (you may need to manually restart to get it to work right) follow these instructions CAREFULLY:

1. Choose your language.

2. At the main screen, choose Disk Utility from the Utilities pull-down menu.

3. Select the drive itself and click on Partition.

4. In the Partition menu, select 1 Partition and Options... where you choose GUID Partition Table. Click OK then Apply, then say "yes" to whatever warning comes up.

5. Once you have reformatted the drive, close the Disk Utility window.

6. Do Not Go Forward. Instead, when you see the main Welcome screen, click the Back button, which takes you to the language select page. It sounds silly but DO IT. This shakes the system into action.

7. Once you have reselected your language and are back on the Welcome screen, click Utilities and select Restore System From Backup...

8. The process should go smoothly from that point on. You simply select appropriate disks to copy your chosen backup data from your Time Machine drive to the new internal drive, as shown in the following sequence:

The Back Story
Originally I tried my swap without first clicking back to the language page, and the installer could not find my new hard drive. Disk Utility saw it and happily formatted it with the GUID partition, but even on the second pass, the installer wouldn't show it as a target option. All I got was this hollow emptiness:
I spoke with Jeerun Chan at Western Digital and asked him to try the same process, which yielded the same results. Then I tried it with another virginal hard drive, this time a 160GB SATA from Seagate. Between the two of us, we ran this test on three different configurations, with the same negative results.

The obvious but depressing solution was to just run the Leopard system installer, then use the migration tool to back up from my Time Machine drive. It's fairly smooth, and smart if you want a clean install on your new drive, but it's boring: it takes a few steps, and they're all obvious. I wanted a bit-for-bit dump from backup to new drive, fully automatic.

As I was installing Leopard on my second drive, the phone rang: it was Jeerun with the crazy back-button technique. I don't know how he thought to do it—I don't even think he knows, but the fact remains: when you have formatted your destination drive and are on the Welcome screen, click the back button and the process will work. If you don't click it, well, in our experience, it seems you will fail in your objective.

Obviously, this won't work if you don't regularly do a full system backup in Time Machine. If the omitted folders in your Time Machine options include system files, you won't be able to do this.

In truth, it might make sense to backup only personal files, especially since this process requires a Leopard install disk even to write the whole image back onto the new drive. Chen swears by SuperDuper, which is perhaps a better pro technique, one that doesn't require a system-install DVD. Still, I wanted to see if this major boast of Time Machine was all that it was cracked up to be. It is, and the end result will be tasty, as long as you don't forget that one little catch.

As with my last Time Machine HDD discovery, this one involves a little hocus pocus. While this method works, you may have your own trick, or a more scientific approach. If so, please share it in the comments below, and spare any fellow Mac users a frustrating afternoon.

Thanks to Jeerun and Heather at WD!