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Partitioning on iMAC


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#1
pdni

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After partitioning my iMAC with 2 partitiions (1 for XP and the other for osx), I could not install OS X on the osx partition. The installer complianed the the selected partition can not boot OS X.

Found something on GUID partition scheme which apparently is what I needed to create the partitions in; however Disk Utility did not not give me that choice when partitioning the internal drive.

Thanks in advance.

#2
chiefsalami

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I'm having a similar problem. I think I may have accidentally repartitioned the disk with the Windows installer, and now I can't install OS X, even though I wiped the partitions and set them back up with the Disk Utility in the OS X installer. Can someone help and let us know how to re-write the partition map? Thanks,

#3
profetes

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Hi,
Yes, this is caused by the partition made by windows installer. It happened to me. So far I could solved the problem through making the imac a target disk and using it as external drive on my ibook, then I could use the utilities of the Mac OS installer disk to repartition the hard disk with GUID choosing it from the options menu, IMPORTANT! Before repartition the HD with GUID, you have to erase the Mac OS partition as Macintosh Extended Journaled, otherwise it won't give the option to choose GUID in the partition section.
Now, I am trying to find a way of doing this without having to erase all my hard disk, because I want to keep my windows installation and then install the Mac OS again.
Profetes

#4
chiefsalami

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Could you please elaborate as to where this GUID option is? I used the OS X installer to try to repartition, and didn't see any mention of GUID anywhere (I was looking for it). I also tried to first erase the disk and then repartition, but it didn't work. I don't have access to another machine (other than my OSX86-ized laptop), and could try a firewire card with it and see if it works correctly.

#5
profetes

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Could you please elaborate as to where this GUID option is? I used the OS X installer to try to repartition, and didn't see any mention of GUID anywhere (I was looking for it). I also tried to first erase the disk and then repartition, but it didn't work. I don't have access to another machine (other than my OSX86-ized laptop), and could try a firewire card with it and see if it works correctly.


The only way of repartitioning the internal HD with a GUID scheme is through another Mac, with the disk utility of the Mac OS X installer. These are the steps:
1. iMac in Target Disk mode
2. Attached to another Mac
3. Open Disk utilities (from 10.4.4 disk) on the other Mac.
4. Erase the volume (the whole HD not a single partition) in Macintosh Extended Journaled. Otherwise is partitioned is MS-DOS (made by windows)
5. Go to Partition tab, select Options and there you should find the GUID scheme
6. Partition the HD

I reckon you can only partition in GUID scheme with another Mac. Not possible in windows, though if you have Mac OS in x86 it should work, I guess.

#6
Jeepboy

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I, too, have dealt with this problem, but I was able to solve it without resorting to Target Disk mode. Here's what I did...

1. Boot the iMac either from another drive or the OS X Install CDs
2. Launch Disk Utility
3. Repartition the disk as ONE partition with the format type set to FREE SPACE
4. Reboot the iMac
4a. If you're booting from another drive, it will tell you that there's an uninitialized disk and ask you if you want to format it - SAY NO, otherwise if you're booting from the OS X Install DVD, it will boot as normal to the choose languange dialog box.
5. Launch Disk Utility
6. Repartition the disk as you need. This time it will be set as GUID partitioning scheme, which is what you need.

Unfortunately, you cannot get access to the OPTIONS button in the partition screen when you're working with the internal disk. Usually, this button would be used to dictate what type of partition scheme you want. This being the case, the above instructions will get it set up as a GUID partition scheme, which is what you Intel Mac needs.

~Jeepboy

#7
profetes

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Hi again,
Actually, there is a simplier way of doing it that the one I explained above.
Go to http://forum.onmac.n...79&postcount=12

It basically says to erase (normal) the volume and not the partitions with the Disk Utility booted with Mac OS installer disk.
Hope it helps

#8
profetes

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Hi,
All these solutions have a caveat: they erase everything, including our brand new windows installation. Someone has posted a UNIX method (via terminal) to reidentify the GUID scheme in the hard disk. I haven't tried yet, it seems risky, but... There it is
http://forum.onmac.n...hread.php?t=136

#9
profetes

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Hi!
I've tried the terminal solution to find the GUID scheme and it worked perfectly...! (so far :D)





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