Modcult

Leopard Installation Partitioning Woes

I ran into a problem trying to install Leopard tonight. The installer showed a red exclamation point on top of my internal hard drive when selecting the target volume and displayed the following error message:

You cannot install Mac OS X on this volume. To enable installation on this volume open Disk Utility from the Utilities menu and repartition the disk as ‘GUID Partition Table’. Note: you will lose all data on the disk by repartioning it.

Not too helpful, huh? Notice Apple’s installation requirements gloss over this requirement:

Mac computer with an Intel, PowerPC G5, or PowerPC G4 (867MHz or faster) processor.

Anyways, I loaded up Disk Utility, selected my target and selected Get Info from the File menu. Sure enough, it listed “Apple_partition_scheme” under Partition Type. There’s the problem. There seems to be lots of confusion regarding this, but the basic rule of thumb seems to be:

• You cant boot a Power PC Mac from an APM partition.
• You cannot boot a PowerPC Mac from a GUID partion.
• You can boot an Intel Mac from a GUID partition.
• You shouldn’t boot an Intel Mac from an APM partition. However, it works. Say for instance you replaced your hard drive and copied the data over at some point from a PPC machine. The Leopard installer will not allow you install onto APM partition on an Intel Mac.

My solution was to backup my entire drive using SuperDuper, reformat the drive (with the GUID partioning scheme), do a clean install [1], and use Migration Assistant to move my files back over.

So a word to the wise: verify your partition scheme using Disk Utility before assuming your Leopard installation will go off without a hitch.

Addendum: I noticed several recommendations in forums stating that even though there was a large red exclamation point and error message, you could double click on the target drive and proceed using the Archive & Install option. I was able to get this menu by double clicking, and when I attempted this route (after having backed up the entire drive as mentioned above) the installation failed. This seems like an installer bug to me.

1: You may prefer to restore your drive prior to the install after the reformat and do a regular upgrade.