View Full Version : Bootable backups for 2 different Mac computers on one external hard drive?

01-06-2009, 10:26 PM
I want use SuperDuper to make bootable back ups onto an external hard drive for both of my computers, (12" Powerbook 1 GHz and a 17" MacBook Pro 2.33 GHz), and I'm wondering if this can be done to one hard drive, but am guessing not because one is a PowerPC-based Mac and the other an Intel based Mac, thus requiring an Apple Partition Map for the 12" as well as a GUID Partition Table for the 17", (if I am understanding it correctly), which doesn't appear to be possible on one hard drive? (Both computers are running 10.5.6 if that matters).

01-06-2009, 10:58 PM
You can't really do that on one drive. Although APM can be used by both, Apple strongly discourages it, and the drive won't show up as bootable in the Startup Disk preference pane.

01-09-2009, 05:32 PM
Suggested reading:



01-09-2009, 08:51 PM

Excellent link, thanks. I am about to add my first Intel Macs to my stable, so my interest isn't 100% academic.

The success of the linked procedure may depend, in a sense, on this paragraph:

"The Mac OS X Installation Disc 10.4.6 included with new Intel iMacs, Mac Minis, MacBooks and MacBook Pros was actually formatted using APM. So despite the confusion about the two different architectures, the different partition formats, and the different boot firmware, there is enough in common among the PPC and Intel systems to make ourselves a nice bootable external drive that we can use to backup both our PowerPC and Intel-based Macintoshes."

Do you know if the Leopard install discs included with the newest Intel machines still retain this feature, i.e., "actually formatted using APM?" Perhaps it makes no difference to the "doability" of the project.


01-09-2009, 11:20 PM
It doesn't matter, actually. APM works with both Intel and Power PC Macs, but as I've said many times here, it's strongly discouraged by Apple (and APM drives won't even show up as a boot option in the startup disk preference pane under Leopard on Intel Macs).

It's best to just stick with APM for Power PC and GUID for Intel.

01-10-2009, 03:15 PM
Thanks Dave, message received.

01-11-2009, 05:26 AM
follow on questions from this thread - useful

I want to do something similar but in fact i want to have three bootable backups + a large media library on an external drive (music, movies, pictures)

1) Imac G5 Running 10.4.11
2) Macbook Pro running 10.4.11
3) Macbook Pro bootcamp partition running XP.
4) Media Files

I figured for ease it would easiest to do this all on one 1.5T disk
(two for the backup swap as i refine the process)

reading a lot of different threads from different sources, i have questions as follows-i plan to use CCC, but could just as easily use superduper.

1) should the backup drive (bud) be formatted in FAT32 (that will work for both mac and bootcamp boots?)
2) should the bud be partitioned, and the partitions formatted differently?
one for mac one for bootcamp/win

3) should i use the disk imaging suggestion below by CCC? This also seems less than perfect. ..
4) will upgrading to leopard make this easier or harder?
5) any thoughts on partitioning the individual computer hard drives. seems not necessary for operating efficiency but may ease backs by splitting out the operating system and data/apps.

Any tactical and sequencing advice appreciated...thought this would be easier than it is! sure i will have some more questions...


"I want to backup multiple machines to the same hard drive, each to its own disk image on the drive"

Sometimes backing up your data to a single external hard drive is just too messy and difficult to organize. Suppose, for example, that you have three computers in your household, and everyone backs up to the same firewire hard drive. Where do you put each person's backup? The single hard drive can't maintain multiple operating systems, Mac OS X does not support that. You could split the drive into three partitions, but that isn't very flexible at all. You could clone each person's drive to a folder on the drive, but that's a little difficult to restore from.

A very good solution in a scenario such as this is to use disk images as the medium of your backup. A disk image is a single file residing on your hard drive that contains the entire contents of another hard drive (except for the free space). When you want to access the contents of that filesystem, you double-click on the disk image to mount the disk image as if it were an external drive attached to the machine. Carbon Copy Cloner 3 leverages disk images to provide you the flexibility of storing several complete, bootable*** backups on a single shared external hard drive. (*** Disk images themselves are not bootable, but you can mount them and restore their content to a physical hard drive to produce a bootable, exact replica of the original).

When you want to copy the entire contents or a selection of data from your hard drive to a disk image, select "New disk image..." or "Choose disk image..." from the target menu. If you want to restore a drive from a disk image backup, boot from a drive other than the target, select "Restore from disk image..." from the source menu and locate the disk image. Choose the drive to which you would like to restore from the target menu.

Learn more about backing up to and restoring from disk images

01-11-2009, 10:30 AM
We have plenty of information about backing up to images in the User's Guide, but in general you shouldn't do this with one drive. You should have separate drives for the Power PC Mac(s), the Intel Macs, and then -- well -- I'd use a Windows backup program, or Winclone, for the Windows volume.

01-11-2009, 11:30 PM

thanks for the quick feedback.
the above post - while dated - suggests quite clearly and with sequencing that it can be done in a simple reliable manner. using superduper?

could you comment any further.

01-11-2009, 11:45 PM
As I've said many times on the forums, while Apple Partition Map formatting will work for your Power PC and Intel Macs, it's strongly discouraged by Apple, to the point where Leopard will not even show the APM partition as bootable in the Startup Disk preference pane.

Since Apple is clearly suppressing these volumes for a reason, I think it's a mistake to do it at this point in time.

01-14-2009, 03:27 AM
i was talking about using a GUID partitioning scheme on the 1.5tb external drive....

with two volumes partitioned as

then doing a full clone of each of the two macs in the respective drives.

was NOT planning on using APM

Many thanks

01-14-2009, 09:49 AM
OK. Your iMac (G5) backup will not be (directly) bootable...