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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 4:51 PM in response to staycoldb

staycoldb wrote:

I can install team viewer if you wanna remote in and run some commands to see the status of the MBR and parttion table. I don't mind. Just want this fixed. Seriously dreading the thought of having to wipe the hdd and start over.

Please do not invite a total stranger on the internet (who you have known for less than 10 minutes) to remote into your system. 😉 Just for your safety and mine as well.

Feb 22, 2014 4:58 PM in response to Loner T

LOL, ya I know. But I know enough to know if they're doing something suspect. Let me check out these tools and I will post back...

Loner T

Level 9

59,513 points

Feb 22, 2014 5:00 PM in response to staycoldb

Once you install the utility, here is an example from my system. Please try it with both /dev/disk0 and /dev/rdisk0.

sudo gdisk /dev/disk0

Password:

GPT fdisk (gdisk) version 0.8.9

Warning: Devices opened with shared lock will not have their

partition table automatically reloaded!

Partition table scan:

MBR: hybrid

BSD: not present

APM: not present

GPT: present

Found valid GPT with hybrid MBR; using GPT.

Command (? for help): ?

b back up GPT data to a file

c change a partition's name

d delete a partition

i show detailed information on a partition

l list known partition types

n add a new partition

o create a new empty GUID partition table (GPT)

p print the partition table

q quit without saving changes

r recovery and transformation options (experts only)

s sort partitions

t change a partition's type code

v verify disk

w write table to disk and exit

x extra functionality (experts only)

? print this menu

Command (? for help): p

Disk /dev/disk0: 1954210120 sectors, 931.8 GiB

Logical sector size: 512 bytes

Disk identifier (GUID): 6ED0C429-00D1-4759-B50E-04B6FB80D0E3

Partition table holds up to 128 entries

First usable sector is 34, last usable sector is 1954210086

Partitions will be aligned on 8-sector boundaries

Total free space is 1293 sectors (646.5 KiB)

Number Start (sector) End (sector) Size Code Name

1 40 409639 200.0 MiB EF00 EFI System Partition

2 409640 1452940543 692.6 GiB AF00 Customer

3 1452940544 1454210079 619.9 MiB AB00 Recovery HD

4 1454211072 1954209791 238.4 GiB 0700 BOOTCAMP

Command (? for help): q

Number88

Level 3

806 points

Feb 22, 2014 5:02 PM in response to Scotch_Brawth

I think the MBR is good but the GPT doesn't look well.

There's an option in gdisk to load the MBR and build a fresh GPT from it - sadly I've never used it and don't know whether that would help you.

It could be an option. 😐

Feb 22, 2014 5:03 PM in response to Loner T

Okay T Loner, is gdisk an alternative cmd line tool to Terminal? I have it installed, but what is the default install location for it? Like I said, I am so new to OSX so forgive my ignorance.

Number88

Level 3

806 points

Feb 22, 2014 5:06 PM in response to staycoldb

In the terminal

sudo gdisk /dev/disk0

should open it

Feb 22, 2014 5:06 PM in response to Loner T

Last login: Sat Feb 22 18:58:44 on ttys000
bryans-mbp:~ Manila$ sudo gdisk /dev/disk0
Password:
GPT fdisk (gdisk) version 0.8.9

Warning: Devices opened with shared lock will not have their
partition table automatically reloaded!
Partition table scan:
MBR: hybrid
BSD: not present
APM: not present
GPT: present

Found valid GPT with hybrid MBR; using GPT.

Command (? for help): p
Disk /dev/disk0: 625142448 sectors, 298.1 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): AEDDB192-5B74-44B1-BA43-EEA9844E2E54
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 625142414
Partitions will be aligned on 8-sector boundaries
Total free space is 2149 sectors (1.0 MiB)

Number Start (sector) End (sector) Size Code Name
1 40 409639 200.0 MiB EF00 EFI System Partition
2 409640 80005903 38.0 GiB AF00 Macintosh HD
3 80005904 81275439 619.9 MiB AB00 Recovery HD
4 81276928 625141759 259.3 GiB 0700 BOOTCAMP

Loner T

Level 9

59,513 points

Feb 22, 2014 5:10 PM in response to staycoldb

On my system (yours should be the same).

type gdisk

gdisk is /usr/sbin/gdisk

Loner T

Level 9

59,513 points

Feb 22, 2014 5:16 PM in response to Number88

Number88 wrote:

There's an option in gdisk to load the MBR and build a fresh GPT from it - sadly I've never used it and don't know whether that would help you.

It could be an option. 😐

I think you are referring to this (the "f load MBR and build fresh GPT from it" option). If OS X boots correctly, it figures out the GPT correctly. The other question would be does using Option key during a powerup show Bootcamp as a valid partition and does it try to boot?

sudo gdisk /dev/disk0

Password:

GPT fdisk (gdisk) version 0.8.9

Warning: Devices opened with shared lock will not have their

partition table automatically reloaded!

Partition table scan:

MBR: hybrid

BSD: not present

APM: not present

GPT: present

Found valid GPT with hybrid MBR; using GPT.

Command (? for help): r

Recovery/transformation command (? for help): ?

b use backup GPT header (rebuilding main)

c load backup partition table from disk (rebuilding main)

d use main GPT header (rebuilding backup)

e load main partition table from disk (rebuilding backup)

f load MBR and build fresh GPT from it

g convert GPT into MBR and exit

h make hybrid MBR

i show detailed information on a partition

l load partition data from a backup file

m return to main menu

o print protective MBR data

p print the partition table

q quit without saving changes

t transform BSD disklabel partition

v verify disk

w write table to disk and exit

x extra functionality (experts only)

? print this menu

Recovery/transformation command (? for help):

Number88

Level 3

806 points

Feb 22, 2014 5:18 PM in response to staycoldb

My bad. The MBR does not agree with the GPT. In the MBR there's a large gap between partitions 3 and 4.

In the GPT that gap does not exist.

Does OSX still boot ok?

Feb 22, 2014 5:20 PM in response to Loner T

Last login: Sat Feb 22 20:15:27 on ttys000
bryans-mbp:~ Manila$ gdisk
GPT fdisk (gdisk) version 0.8

Type device filename, or press <Enter> to exit:

Feb 22, 2014 5:21 PM in response to Number88

88, yes, I have to hit 'option' to choose OSX, but OSX is still booting ok

Feb 22, 2014 5:24 PM in response to staycoldb

what should I input for device filename? I'm assuming this is the hdd?

Number88

Level 3

806 points

Feb 22, 2014 5:27 PM in response to staycoldb

sudo gdisk /dev/disk0

Feb 22, 2014 5:33 PM in response to Number88

O, nevermind, I misread Loner's reply. He was giving me the path to gdisk and I mistook it for syntax.

88, the output for that command is already above

Repairing Boot Camp after creating new partition