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10.4: How to enable booting from multiple clones System 10.4
I'm a big fan of using SuperDuper (or CarbonCopyCloner or even Disk Utility) to make bootable clones of my startup volume as an important part of my backup strategy. In fact I like to not only keep a most recent clone, but several historical ones as well.

So I was delighted when I recently discovered I could buy 500GB and 750GB external FireWire hard drives for under $200, and assumed I could simply format them into multiple boot-volume-sized partitions into which I could place clones, as I had so often and easily in the past. However, I eventually became dismayed when I later discovered that while I could use SuperDuper and other programs to create multiple clones, the only clone that I could actually boot would be the first bootable clone in partition order encountered on the drive.

With a hint from an Apple Genius, I eventually discovered the source of my difficulty. Whereas at some point in the past Disk Utility would use Apple Partition Map as the default partition format, appropriate for booting volumes on a PPC Mac, that is no longer the case in Tiger. Instead I discovered that Disk Utility was using the Master Boot Record format appropriate for Windows; probably because it discovered that, as shipped, the new drives were already pre-formatted with this Windows-centric partition format.

It is quite simple to determine what partition table format has been used on your internal or external hard drives. Simply run Disk Utility, select the drive of interest (not one of its individual partitions), select the Partition tab, and look at the last line displayed at the bottom of the window after Partition Scheme:. You should discover one of three alternatives:
  • Master Boot Record - appropriate for DOS & Windows
  • Apple Partition Map - appropriate for PowerPC Macs
  • GUID Partition Table" - appropriate for Intel-based Macs
As long as you don't have a compelling need to boot from a clone saved to a partition, the format may not matter. It has also been rumored that this restriction may be relaxed in 10.5, though I haven't tested that. But with Tiger 10.4.10 at least, if you want the ability to boot from a choice of multiple clones stored in various partitions of a drive you should explicitly set the desired Partition Table format at the time you partition the drive.

This too is quite simple. In the Partition tab of Disk Utility, where you set the number and size of the partitions, make sure you click on the Options button to select the desired partition format prior to pressing the Partition button that performs the work.

Backup early, backup often, and partition well.
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10.4: How to enable booting from multiple clones
Authored by: mpanighetti on Nov 02, '07 08:12:53AM

I'm fairly certain that this is how Disk Utility always handled partitioning. Unless you specify a different partition scheme, it will stick with however the drive is already formatted. If you use an unformatted hard drive, it will pick the partition scheme appropriate to booting the Mac to which it is attached (APM for PowerPC, GPT for Intel).



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10.4: How to enable booting from multiple clones
Authored by: steresi on Nov 02, '07 08:25:08AM
I was delighted when I recently discovered I could buy 500GB and 750GB external FireWire hard drives for under $200...
Please do tell where you've had good experience ordering such low-priced drives!!

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10.4: How to enable booting from multiple clones
Authored by: seika7 on Nov 02, '07 08:49:37AM

Costco and CompUSA



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10.4: How to enable booting from multiple clones
Authored by: Reddog on Nov 02, '07 12:05:22PM

I bought my 500GB external Firewire drive from Fry's for $120 (on sale).



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10.4: How to enable booting from multiple clones
Authored by: las_vegas on Nov 02, '07 10:13:23AM

You can change the partitioning scheme of any drive by clicking the "Options" button after selecting a Partition Scheme. You can also install multiple bootable partitions on the drive and select from them via the Option key on boot.



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10.4: How to enable booting from multiple clones
Authored by: johnsawyercjs on Nov 02, '07 01:12:22PM

Whenever I buy a pre-formatted drive, that's been formatted as a Windows volume, but which I don't plan to use under Windows, I use Disk Utility to erase (and optionally partition) the drive before I start putting Mac files onto it. Disk Utility's default for erasing a drive, is Mac OS Extended (Journaled). That would take care of the issue discussed here.



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10.4: How to enable booting from multiple clones
Authored by: barryjaylevine on Nov 02, '07 10:17:18PM
Actually, "MacOS Extended (Journaled)" has nothing to do with what is being discussed here. We're discussing the partitioning of the drive and that requires the GUID scheme is you intend to boot an Intel Mac with the subject drive.

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Two things in this world aren't overrated: Macintosh and Lemon Meringue Pie.

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10.4: How to enable booting from multiple clones
Authored by: johnsawyercjs on Nov 04, '07 05:46:58PM

A straight erase of the hinter's drive, in Disk Utility's "Erase" tab, while leaving the default option for Mac OS (Extended) selected, would have changed the volume's partitioning to APM or GUID, and so would have fixed the hinter's problem, but without giving him control over whether the volume was APM or GUID. The hinter doesn't mention whether he was using his drive with an Intel or PPC Mac, so we don't know if he needed to choose between APM or GUID, but it seems that Disk Utility's Partition tab will kill two birds with one stone, if necessary (both reformatting the volume, and letting you select the type of partitioning). As mpanighetti says above, Disk Utility's Erase option will pick the volume format appropriate for booting the Mac model that it's being run on--APM for PPC, and GUID for Intel--it has to choose one or the other, since there's no MS-DOS/Master Boot Record form of Mac OS (Extended)--so an erase as a Mac OS (Extended) volume would probably have given the hinter just what he needed.



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10.4: How to enable booting from multiple clones
Authored by: las_vegas on Nov 04, '07 10:15:28AM
The GUID Partitioning scheme is necessary for installing OS X on an Intel Mac, not necessarily booting one. I have successfully cloned an Intel image onto a drive using the Apple Partition Map and it worked. Placing a copy of Leopard (10.5) allows for a drive that will boot any PPC Mac as well as most Intel Macs. Although I can't confirm it; It's my understanding that some of the newest Intel Macs require GUID to boot.

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10.4: How to enable booting from multiple clones
Authored by: johnsawyercjs on Nov 04, '07 05:49:38PM

From what I understand, this requirement for GUID has been confirmed for the 24" Aluminum iMac.



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