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About partition maps and non-bootable FireWire drives System
I recently discovered the following while trying to get my Mac Mini to boot from a FireWire drive.

I'm a recent switcher. I took some leftover PC parts I had, and combined them with a Mac Mini to make a pretty decent machine. One of those pieces was a 160GB hard drive originally used in a Windows machine. I popped the drive into a FireWire enclosure and connected it to the Mini. I formatted it as Mac OS X Extended (Journaled), and stored media on it for a while with no problems. When I got tired of my slow internal drive, I decided to run the system entirely from the FireWire drive.

I used Carbon Copy Cloner (CCC) to clone my existing installation to the FireWire drive and rebooted, but I couldn't for the life of me get OS X to boot from the drive! I then formatted a very old hard drive and CCC'ed a clean OS X installation onto it, and it was able to boot. After some sleuthing, I figured out the problem:

To boot from a FireWire drive, the drive's partition map must be in the Apple Partition Map format, not the PC Partition Map format.

This is changeable via the Partition tab when you select the disk in Disk Utility (the disk itself, not just the partition.) When I had originally connected the drive, it allowed me to format it as an OS X partition, but it didn't change the format of the partition map itself. A quick reformat and re-CCC, and I'm booting from the FireWire drive!
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About partition maps and non-bootable FireWire drives
Authored by: greyDel on Feb 02, '06 07:23:37AM

I'm not sure you have to use CCC. I simply used Disk Utility to "restore" my PowerBook installation to my iPod and can actually run Mac OS X from my iPod.



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This was covered in TidBITS
Authored by: Mechanist on Feb 02, '06 08:38:05AM
See Jonathan Rentzsch's article which covers this in detail.

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But this hint made some things clearer
Authored by: tmerritt on Feb 02, '06 11:53:37AM

This was exactly the problem I've been trying to figure out for a couple of days. I read the Rentzsch article yesterday but it took this hint to make me remember months ago I had formatted the drive with FAT32 in a FW/USB enclosure for use with a PC and my Mac on our home network. I thought I could just erase it (without *partitioning* it) and use it just for backing up my Mac.

So, I erased it and used Disk Utility to restore the Mac onto it... fine. Tried to boot from it... got the gray Apple logo on the white screen for a few seconds, and the the logo would suddenly move lower on the screen a handful of pixels, and the machine would hang without the startup cycling graphic. I'd do a full erase, restore to it again, same thing. Tried it with another Mac at work. Same thing.

Then I read this post. I partitioned it with Apple Partition Scheme, restored to it, and bingo.

Thanks.



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About partition maps and non-bootable FireWire drives
Authored by: Ptitboul on Feb 03, '06 05:17:02AM
This other hint http://www.macosxhints.com/article.php?story=20030613121738812 also describes how to have simultaneously the pdisk partition map (so you can boot on the disk) and the fdisk partition map (so you can read it on a Windows PC).

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more precise link
Authored by: moritzh on Feb 03, '06 11:24:37AM

That's right, I've been using that method to create a both a HSF+ and a MS-DOS partition that are booth bootable on their respective OS, it's great.

There are very many comments, I was trying to post a link to the proper one, but somehow I just can't figure out how to do it (since it is a comment at the top level, it always displays together with all other top level comments when clicking the link), so here is the manual method: Look for the following comment:

"Authored by: silentaccord on Fri, Apr 15 '05 at 06:32PM"



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Internal drives, too
Authored by: piper on Feb 03, '06 07:54:43PM

This is also important to understand when installing a new hard drive in a mac (especially in a laptop - they're such a pain to take apart!). I recently had to install a new hard drive in an iBook whose drive had failed and I had to erase the partition map in order for the OS X installer to recognize the new drive.

piper



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