Thread: Time Machine - You can't restore this backup ... different model of Mac HOW TO

I have just suffered from and solved this issue after a couple of hours work, so here's the documentation for prosperity and the sake of future Googlers.

I installed 10.6.3 using nawcom ModCD, set up the system and made a Time Machine partition. The idea being that I could try delta updates ... I never got 10.6.4 to boot with my video card (even using the same kexts etc as I created for 10.6.3, but that's a whole other story), and 10.6.4 doesn't really have anything I need, so I decided to give up and restore. BUT the system restore utility on the installation disk wouldn't let me ... I got the following enigmatic message: You can't restore this backup because it was created by a different model of Mac

To quote someone on the hackintosh.nl forum; "Nou, mooi niet!". The problem was the system identifier in the nawcom ModCD preboot.dmg smbios.plist. It's set to something amusing like osx86hack1,1, so what I had to do was create a new boot CD with the string that matches the system identifier my mac has (iMac8,1). Unfortunately this isn't totally straightforward - you can edit an iso or copy it with Disk Utility and edit stuff if you do it right, but you won't get a bootable cd out of it, no matter how many coasters you want to go through.

After a lot of googling, the tool you need to create the boot disk is hdiutil, a command line utility that comes with the mac. Here's what I did:

1) I dragged preboot.dmg out of the boot cd onto the desktop, opened up smbios.plist, edited the system identifier (SMproductname), saved the plist and ejected the dmg (I then opened it up again to check my plist had been saved properly, then ejected it again)

2) I created a folder on the desktop called "newcd" and dragged the contents of the boot cd onto it

3) I dragged my edited preboot.dmg to this new folder, overwriting the old preboot.dmg

4) In order to create a hybrid bootable cd I needed to locate the file "cdboot" on my particular cd - nawcom had placed it in ./usr/standalone/i386

5) I executed the follwing command:

Code:

hdiutil makehybrid -o ~/Desktop/MyBootable.iso "~/Desktop/newcd/" -iso -hfs -eltorito-boot "~/Desktop/newcd/usr/standalone/i386/cdboot" -no-emul-boot -hfs-volume-name "MyBootCD"

6) I burned it with toast

And it worked. It boots and I am able to restore the whole system from time machine backup.
Huzzah!

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Further to the above;

A full time machine restore from backup takes over an hour - plus the time spent creating the CD as above.

Whereas wiping the disk, doing a fresh install, and choosing the "transfer my information" option during the first system boot is probably comparable, and involves no fiddling with bootable CDs. It may be a little upsetting to wipe your system disk, but it is probably less hassle overall.