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Scotch_Brawth Author

Level 3

827 points

Repairing Boot Camp after creating new partition

I'm running OS X 10.8 and Windows 7 x64 Pro.

After properly setting up Boot Camp to dual-boot Windows on my Mac mini, I decided to test whether or not it was true that creating another partition (a data partition for OS X) would interfere with Boot Camp. Wikipedia claims it does interfere but without citing a source, whilst the Boot Camp documentation itself only specifies that the disk must be a single partition _prior_ to setup - there's no mention of whether the disk must be _kept_ that way afterwards.

I opened Disk Utility, reduced the size of my OS X parition from 420GB to 80GB, and created a new partition in the unallocated space. Here's how it looks now:

When I attempted to proceed with the process, I did receive a warning that doing this (and I quote), "may" cause problems with Boot Camp. Seeing as it was inconclusive, I thought I'd give it a shot - nothing ventured…

Of course, it borked Boot Camp, otherwise I wouldn't be posting here. Whilst OS X boots just fine, the Boot Camp partition now no longer shows up in the Startup Manager, though it does in the Startup Disk prefPane. If I do attempt to boot into Boot Camp, I receive the following message on a black screen:

No bootable device --- insert boot disk and press any key

The advice given to someone who had this same problem was, "fix your damaged Boot Camp volume." But I'm at a loss as to how to do that.

So, anyone know how to proceed now so that I can keep my partitions as is, whilst fully restoring normal Boot Camp functionality?

Mac mini (Mid 2011), Mac OS X (10.7.4)

Posted on Jul 26, 2012 11:28 PM

1,534 replies

Loner T

Level 9

59,513 points

Feb 22, 2014 5:36 PM in response to Number88

The EFI part looks good.

OSX

GPT: 2 409640 80005903 38.0 GiB AF00 Macintosh HD

MBR: AF 1023 254 63 - 1023 254 63 [ 409640 - 79596264] HFS+

These do not agree.

Recovery looks good.

Bootcamp is a mess.

GPT: 4 81276928 625141759 259.3 GiB 0700 BOOTCAMP

MBR: 07 1023 254 63 - 1023 254 63 [ 204806144 - 420335616]

What happens when you try to boot Windows? Do you get Operating System not found error?

Feb 22, 2014 5:38 PM in response to staycoldb

Loner, when I try to boot windows I get "disk read error, press ctrl+alt+delete to restart".

Number88

Level 3

806 points

Feb 22, 2014 5:40 PM in response to staycoldb

I see.

The MBR has your Bootcamp partition starting at sector 204806144 but the GPT has your Bootcamp partition starting at sector 81276928

So the resizing worked at least to some degree.

I am presuming that the GPT was not updated by the tool you used.

The problem is, if we make a new GPT from the MBR Windows may still refuse to boot.

If we make a new hybrid MBR we don't know at this stage which start sector gdisk will use.

It may be an option to use testdisk to recover the old Windows partition and then build a new hybrid MBR with those details.

It's still possible that this will fail to boot Windows.

What does Loner T think?

Number88

Level 3

806 points

Feb 22, 2014 5:51 PM in response to staycoldb

Has Windows been successfully booted since you resized?

Feb 22, 2014 5:54 PM in response to Number88

Nope. I ran the tool in windows, rebooted the machine and immediately got that disk read error. So no, I can't get into the windows partition at all.

Number88

Level 3

806 points

Feb 22, 2014 6:00 PM in response to staycoldb

So at that point Windows was still a boot option in the boot menu?

It may be that Windows is hosed anyway. It would probably need a chkdsk running anyway.

As I see it you could go through a whole lot of work recovering the original Windows partition with testdisk and creating a new hybrid MBR with gdisk using those older start and end sectors and Windows might still not boot.

I'd be more concerned with saving OSX than Windows - which in itself may not work.

I'm sure that disk utility won't allow you to delete the Windows partition now.

That *may* be possible with gdisk and a new protective MBR could be created with gdisk. If that works then OSX could be saved.

Otherwise it will mean formatting the disk and re-installing everything.

Sorry it's not better news.

What do you think Loner T?

Feb 22, 2014 6:05 PM in response to Number88

Ugh. Please have better news T Loner :|

Loner T

Level 9

59,513 points

Feb 22, 2014 6:10 PM in response to Number88

1. If OS X boots correctly, AND, the Bootcamp volume is visible, one option is to extract the data from the read-only NTFS side and delete the windows partition completely.

2. Since Recovery is intact, OS X can be reinstalled after turning the entire disk into one partition. Worst case an erase and format and OS X re-installation, followed by a new bootcamp installation, and then restoring files as necessary to windows from the saved NTFS (preferably to an external drive).

3. The assumption in 2 is that no OS files, but only user files need to be restored.

4. Testdisk is a very time-consuming, but viable option.

PS: Not sure how much can be saved from step 1, especially based on locations of files on the disk.

Message was edited by: Loner T

Feb 22, 2014 6:12 PM in response to Loner T

Well I don't know anything about testdisk or how to use it, and I don't expect anyone to devote their time to walking me through all that.

I don't have a physical copy of OSX at the moment. Is there a tool in OSX to create a recovery disc so I can reformat?

Loner T

Level 9

59,513 points

Feb 22, 2014 6:15 PM in response to staycoldb

1. In this thread, there are examples of testdisk.

2. If you are on ML or Mavericks, you can do internet recovery without any media. Lion can also be recovered, possibly using Target Disk Mode if there is another available MAC and Firewire and/or Thunderbolt connectivity is possible.

What version of OS X do you have on the machine, StayColdb?