I did manage to get Snow Leopard installed

So, after many failures, I did manage to get Snow Leopard installed on my iMac yesterday. After getting more comfortable with the backups of my important data, I decided that I would just wipe my boot drive clean and do a fresh install. When you boot off of the Snow Leopard DVD, you have the option of firing up Disk Utility and formatting your boot drive for a fresh install. However, you also have the option of restoring from a Time Machine backup.

Even though all of my Time Machine backups were from my 10.5 install, I decided to try and see if I could restore a 10.5 Time Machine backup into a new install of Snow Leopard. While the installer seemed to let me proceed, the actual restore failed, for reasons that don't appear to be related to Snow Leopard. The drive situation on my iMac looks like this:

I have instructed Time Machine to backup the contents of both the 250GB and 750GB drives onto the 1TB drive. This appears to work fine, as I have done spot checks and found content from both drives in the Time Machine backups on the 1TB disk. However, the logic for restore appears to be stupid -- the restore code calculates the size of a backup (in my case, around 730GB), and attempts to restore that data onto the primary drive. Which obviously, isn't going to work in my setup.

So one fallout from the Snow Leopard install is that I probably can't restore my machine if my 250Gb drive dies, which is a chilling thought.

As I started to think through how I would get my machine back if I wiped the boot drive, I decided it was worth taking another pass at Google, and doing some things that were considered to be more risky (if I'm going to blow the drive away anyway, why not risk a little data corruption first?). This forum thread on InsanelyMac contains a post from Rod Smith, author of GPT fdisk (a Linux fdisk clone that supports GPT partitions). In his post, Rod mentined that it might be possible to use gdisk to muck with the "hybrid MBR", that can be written to the GPT partition via Bootcamp. Well, this rung a bell, because I had used Bootcamp about a month ago in my quest to get Ubuntu 9.04 installed on my Mac, for something that I was researching (and maybe will write about one day).

So, throwing all caution to the wind, I downloaded gdisk and started poking around. Going into expert mode and rebuilding the MBR didn't work for me. However, I used gdisk to nuke both of the Linux partitions (OS and swap) from my Linux install. Apple's Disk Utility (both in its 10.5 and 10.6 incarnations) was unable to remove these partitions, but gdisk nuked them with ease.

With those partitions out of the way, Snow Leopard installed like a champ. My guess is that Apple's Snow Leopard installer punts if it sees any unrecognized partitions on the startup disk -- so if I had had Windows installed, it probably would of worked, but Linux is a definite no-go.

-Andy.