Users/Guides/Emergency Repartition
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[edit] Be careful
If you want to wipe everything out and go back to your original system, beware of a potential serious problem: GUID partition scheme.
When you run XP_ON_MAC (a.k.a. xom.efi), the software will convert the Mac-native GUID partition scheme to the standard PC partition scheme that windows knows how to use. Mac also knows how to use this scheme, because it is the industry standard on USB drives.
The problem is that the OS X installer refuses to let you install it on a non-GUID partitioned drive, claiming that it is "non-bootable". The drive is in fact bootable, because I have booted from a drive that the installer claimed was non-bootable. A more accurate phrase would be "non-installable by OS X installer".
[edit] Problem 1
If you boot from your original install DVD, and choose to re-partition your internal HD, it may result in having a disk that will not be bootable, and the install program will refuse to proceed. The problem is that the partition scheme MUST be 'GUID partition' in order for an Intel Mac to boot on, and it is 'fdisk' instead.
The solution given by apple support is the following: http://docs.info.apple.com/article.html?artnum=303220-en
Unfortunately, the disk utility on your install DVD disables the "option" button that offers the option "GUID partition" : this option is only available for external disks! Since the Mac hardware was not intended to ever be running a non-GUID partition scheme, it is almost half-way logical that the developers left this option out. But have no fear; there is still a very simple solution.
[edit] Solution 1.1
(This solution does not require a second Mac, and is the easiest solution.)
- Run the install DVD on the ill Mac (put in the DVD, then power on and press and hold the "c" key when you hear the chime)
- Open Disk Utility
- Click on the physical disk (the DISK, not the partitions)
- Choose the Erase Tab
- Enter a name; choose the Mac OSX Extended (Journaled) file system type
- Press Erase
This will create a new partition table. If you need to, you can now go to the Partition tab in Disk Utility and re-do your partitioning -- this time as GUID partitions rather than MBR partitions.
[edit] Solution 1.2
(Requires second Mac)
- Put your install DVD (the one you got with your Intel Mac) in another Mac (Intel or PPC).
- Connect the Macs with a firewire cable
- Boot your Intel Mac in firewire mode, by pressing T during boot time.
- Open the disk utility that is on the install DVD
Then, you can re-partition the internal disk of your Intel Mac, with "GUID partition scheme" chosen by clicking on the "option" button.
NOTE: The external machine can't be PPC - if you don't have a 2nd Intel Mac available use #Solution 1.1 above instead. I tried repartitioning my MBP internal drive via a PPC Mac Mini and Firewire Disk Mode. Although the options button does appear, the GUID partition scheme option does not. See Rich Trouton's Apple Blog article for an explanation of why - PPC machines don't support GPT. You can get the internal disk setup properly by erasing it completely in Disk Utility as described in #Solution 1.1. Click on the drive and then the info button to verify that "GUID_partition_scheme" is there.
[edit] Problem 2
If you have attempted to create a "Free Space" partition, and then later create a filesystem in this free space later (which is what I tried), you may end up with a system that will not boot. If you try to recover using the OS X Installation DVD ([[#Solution 1.1] above), the Disk Utility will hang when trying to access the drive. I do not know if #Solution 1.2 above will work or not, but I did not have an extra Intel Mac available.
[edit] Solution 2.1
What worked for me was booting from the LiveCD available from the mactel-linux site: mactel-linux. I then simply ran "parted", and then removed all of the partitions, which seemed to repair the disk's partition table. I could then continue using #Solution 1.1 above.
