Small Partition for Repair?

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Level 1

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Small Partition for Repair?

I recently got a 24" iMac and want to establish a small partition on an external firewire disc to be used for emergency repairs on the internal disc. I did this on my previous 1Ghz flatpanel, but of course the PPC system installed there wouldn't work on the Intel iMac. The partition is only 7Gb, so cloning my system and library from the main system disc won't work (they are too big ). I need an abbreviated version of the System, Library, etc. to fit. The iMac system DVD install disc won't recognize the partition to install there.

Any suggestions?

24" iMac Mac OS X (10.4.7)

Posted on Jan 1, 2007 3:25 PM

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Answer 1

Anne Bras

Level 4

1,760 points

Jan 1, 2007 3:42 PM in response to glassetcher

The external HD does need to be partitioned with the "GUID Partition" Scheme. Otherwhise the Intel Mac's can not boot from it. Your external HD is partitioned with the "Apple Partition Map" Scheme, which will only work for the PPC Mac's to boot from. Both PPC and Intel Mac's can boot from the new "GUID Partition" Scheme.

Only solution:
- Copy the file's on the external HD to your iMac
- Repartitionate the HD with Disk Utility
Make sure you use the "GUID Partition Scheme" from the options menu
- Put back the file's on the HD
- Boot from the installation DVD
- Now the installer will be able to install OSX on it.

It is not possible to convert the "Apple Partition Map" Scheme to the new "GUID Partition" Scheme.

Hopefully this is helpfull or solved your problem. Consider rewarding some points!
Please see the "helpfull" and "solved" button's on top off this message! Apple: Why reward points?

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Answer 2

glassetcher Author

Level 1

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Jan 1, 2007 3:43 PM in response to Anne Bras

Thanks! As Johnny Carson would have said "I did not KNOW that!" All of my searches that recommended using Carbon Copy Cloner, SuperDuper, etc, never mentioned a problem with the partitioning with the PC Disk Utility vs. the Intel Disc Utility. (or at least I didn't find any mention of it)

I'll give it a try.

Thanks again!

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Answer 3

Kappy

Level 10

361,741 points

Jan 1, 2007 3:54 PM in response to Anne Bras

Anne,

Intel Macs can boot from drives formatted with the Apple Partition Map. However, the installers will not permit installation of OS X on a drive that is partitioned with APM. You may, however, clone an existing Intel OS X system to an APM partitioned drive. You will then be able to boot an Intel Mac from that drive.

I am under the impression that PPC Macs cannot boot from GUID partitioned drives. You stated in your post that they can. Do you have a reference for this? I'd appreciate your passing it on to me.

Happy New Year!

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Answer 4

Anne Bras

Level 4

1,760 points

Jan 1, 2007 4:11 PM in response to glassetcher

Quoted: Do you have a reference for this?
Someone at the Apple Care Center told this to me. Although i'm not 100% sure!

I did not know it was possible to boot from the Apple Partition Map with a Intel Mac. Thanks for telling me!

Happy New Year!

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Answer 5

Kevin Horn

Level 4

1,836 points

Jan 1, 2007 4:00 PM in response to glassetcher

There is also Tech Tool Pro which can create just such a small partition on your main drive that you can boot from for repairs with no muss or fuss, literally just a single click, and using very little disk space.

Kevin

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Answer 6

The hatter

Level 9

60,980 points

Jan 1, 2007 4:04 PM in response to glassetcher

7GB is a tight fit. I would have gone for a little extra head room like 12GB. TechTool Pro 4.5.2 had to increase the eDrive slightly (again) and of course you might want/need to update it to Leopard or something someday.

Search for "GPT" or GUID in the forums or Apple Support. Hopefully it will make it into Mac 101 Help & Troubleshooting - or it will be a mute point and every system will use GPL, which began with 10.4.4.

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Answer 7

Anne Bras

Level 4

1,760 points

Jan 1, 2007 4:17 PM in response to The hatter

Interesting Page:
http://docs.info.apple.com/article.html?artnum=303220
See the bottom off the page!

A PowerPC-based Mac can only install Mac OS X on a disk with the "Apple partitionscheme."
An Intel-based Mac can only install Mac OS X on a disk with the "GUID partitionscheme."

Quoted from The Hatter: 7GB is a tight fit.
If you install OSX with everything deselected at the custom install option the installation does need about 2 gig off space. If the Partition is 7 GB you will have 5 gig off free space.
A "fail-safe" boot drive does not need all the applications, just only the file's needed to start-up the Mac.
The "fail-safe" partition on my Lacie FireWire drive is only 4 gig and has always worked fine!

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Answer 8

Kappy

Level 10

361,741 points

Jan 1, 2007 6:51 PM in response to Anne Bras

Interesting Page:
http://docs.info.apple.com/article.html?artnum=303220
See the bottom off the page!

A PowerPC-based Mac can only install Mac OS X on a disk with the "Apple partitionscheme."
An Intel-based Mac can only install Mac OS X on a disk with the "GUID partitionscheme."

Anne,

That's correct - you cannot install because the installers prevent it. But you can clone an existing installation. I assure you it works because I've done it as have many others.

But, I'm pretty sure you cannot boot a PPC Mac from a PPC system installed on a GUID partitioned drive.

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Answer 9

Anne Bras

Level 4

1,760 points

Jan 2, 2007 1:40 AM in response to Kappy

Kappy: But, I'm pretty sure you cannot boot a PPC Mac from a PPC system installed on a GUID partitioned drive.

Take a look on this page:
http://www.macfixit.com/article.php?story=20060721104222189

Quoted:
The reason is that there is no way to boot from a GUID partition on most PowerPC-based Macs (aside from the very newest G4 and G5 systems).

I have just tried it. My Powermac G5 (2x2.3) can boot from my external FireWire GUID partitioned HD!

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Answer 10

Kappy

Level 10

361,741 points

Jan 2, 2007 8:09 AM in response to Anne Bras

Yes, that was my assumption. But in your first reply to the OP was this sentence: "Both PPC and Intel Mac's can boot from the new "GUID Partition" Scheme." I see now that was simply a misstatement due, I'm sure, because English is not your first language. I just wanted to be sure I hadn't missed something. Sorry for my confusion.

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Answer 11

The hatter

Level 9

60,980 points

Jan 2, 2007 8:23 AM in response to Anne Bras

Take a look at Apple Developer Doc: The Road to GPT

Apple's Support for GPT

Any Macintosh computer running Mac OS X 10.4 and later can mount GPT-partitioned disks.
Intel-based Macintosh computers can boot from GPT. By default, the internal hard disk is formatted as GPT.
IMPORTANT: While Intel-based Macintosh computers can boot from GPT and APM, Apple only supports booting Mac OS X on these machines from GPT. Apple's GUI tools, like the Installer, will prevent you installing Mac OS X for an Intel-based Mac on non-GPT disks.
On all Intel-based Macintosh computers (and, starting with Mac OS X 10.4.6, PowerPC-based computers as well), Disk Utility has full support for GPT. The diskutil command line tool also includes GPT support. See its man page for details.
Note: If you're using a PowerPC-based computer running Mac OS X 10.4.6, you'll be disappointed to discover that the diskutil man page has not been updated for GPT. Rest assured that the actual diskutil code is GPT-aware. Use the tool's built-in help to learn how to create a GPT disk.

Mac Pro 2GHz 4GB 10K Raptor 23" Cinema Mac OS X (10.4.8) WD RE16 RAID DW 4.0 APC RS1500 Vista RC1

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Answer 12

Anne Bras

Level 4

1,760 points

Jan 2, 2007 8:44 AM in response to Kappy

Quoted: I'm sure, because English is not your first language.

Yeps!
Sorry for the misunderstanding i caused!
I always try to be as clear as possible, but this does not always work with my poor english.
I'm trying to improve :)

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Answer 13

Kappy

Level 10

361,741 points

Jan 2, 2007 9:05 AM in response to Anne Bras

Anne,

Don't apologize. You do extremely well. Better than most for whom English is not a first language. I never have a problem understanding your posts. This particular case was simply a misstatement; very easy to make when you're busy on the forums. I've done them too.

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Answer 14

glassetcher Author

Level 1

0 points

Jan 2, 2007 6:11 PM in response to glassetcher

So I took all of your advice and unloaded all of the files off of one of my external discs and then reformatted GPT. The iMac software install disc then recognized the partition and I loaded a stripped down version of the OS. It took only a little over 5 Gb, so the 12 Gb I partitioned was maybe a little overkill. Oh well, room to grow later.

Since I have another 250Gb disc on which I also have a repair partition, rather than go thru the process of moving all of the files off of that disc and re-partitioning, I just cloned the repair partition from the first ext disc to the second one. Worked fine. So, now ext disc #1 is GPT partitioned and disc #2 is APM partitioned.

Works so far. Do you see any problems in the future with this setup?

Thanks for your help!

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Answer 15

Kappy

Level 10

361,741 points

Jan 2, 2007 6:20 PM in response to glassetcher

As long as you don't try to install two versions of OS X on the same volume, it sounds fine to me.

As for the future who knows.

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