10.5: Create a single Intel+PowerPC diagnostic drive

Oct 31, '07 12:30:00PM

Contributed by: brett_x

There are many purposes for a single partition to boot multiple architectures. Running diagnostics and repair utilities is just one of them. You can use this tip for many other purposes as well.

Background: Tiger only allowed you to boot either an Intel or a PPC Mac, but never was there a choice for a heterogeneous boot partition (without some drastic measures; here's one hint) because the binaries are different. Leopard gets one step closer because they are the same binaries. One might think that you could easily build a diagnostic drive out of an old FireWire drive that will boot either Intel or PowerPC machines. And you can, but there's a catch. Intel Macs can "only" boot to a drive that is partitioned using the GUID partition table scheme, while PowerPC Macs can "only" boot to a drive that has an Apple Partition Map scheme.

The exception is for the Install DVD. You can boot either kind of Mac using the same DVD. I believe that this is because of the special partition map that DVD's use. In any case, you can use this to your advantage if you need to make a single drive that can boot either type of machine. This is especially helpful for people who support multiple CPU types in their Mac OS life.

Disclaimer: Please be sure that you have the appropriate legal rights to follow these steps before proceeding (i.e. be sure to own enough copies of Leopard for the number of machines you intend to support with this disk.)

What you'll need:

  1. A Leopard Install DVD or a disk image of it (i.e. from Apple Developer Connection).
  2. A Leopard diagnostic partition. You can just do a base install for now and add your diagnostic utilities later, or you can configure this partition as you would like your diagnostic drive. Consider doing a custom install and installing only what you will be using in your diagnostic environment (i.e. no printer drivers or bundled applications).
  3. Another "primary" partition running OS 10.4 or later, with Carbon Copy Cloner, version 3 (CCC3). It *can* be the Leopard diagnostic partition, but that isn't ideal for a number of reasons. You're better off if you have another partition to use.
  4. A FireWire drive that is big enough to accommodate the files you'll need on the Leopard diagnostic partition, plus 1GB to 2GB of additional space. Note that it does not have to be as big as the Leopard diagnostic partition, just the total size of the files, plus an extra 1GB or 2GB for a swap file and other temp files.
The steps:
  1. Boot to your primary partition.
  2. Insert your Install DVD or mount the disk image of it. Use CCC3 to clone your Installer DVD (source) to your FireWire drive (target). Under Cloning options, select Copy Everything from the source to the target, then check Erase the target volume and Require block-level clone.

    When this step is done, you will have a FireWire disk that will install Leopard faster than the DVD, but that isn't the point of this tip. (Take it as a bonus tip if you ever find the need to install Leopard on a number of machines.)
  3. Next use CCC3 to copy all of the files from your diagnostic partition (source) to the FireWire disk (target). This time, use Copy selected items under Cloning options. Also check Delete items that don't exist on the source. This step will take a long time.
When you've finished the clone, it should be bootable by either an Intel or PowerPC Mac. I don't recommend using this as a primary drive. It will likely be slower due to the limitations of the DVD partition scheme, but it should do the trick if you're looking to have just one drive to boot multiple architectures.

Note: if some of your applications end up looking like folders instead of applications, just rename them with an ".app" at the end. Also, be sure to consider a donation to the author of Carbon Copy Cloner if this works out for you; he makes this and many other Mac OS X hints possible.

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