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Windows 7 Bootcamp MBR has gone AWOL. Any ideas on getting it back?

Had a sound bug in Windows, so I figured a soft reboot wouldn't hurt. Guess I was wrong. Instead of zipping right back into Windows, the machine (a Mac Pro 3,1) hangs on white and can't boot into Windows. I've had a similar problem in the past, but was never able to nail down the cause. (I think something's looking at my MBR and deciding it's free space instead of protected, but that's a guess).


Here's the output of a "sudo gpt -r -vv show disk0"

gpt show: disk0: mediasize=250059350016; sectorsize=512; blocks=488397168

gpt show: disk0: Suspicious MBR at sector 0

gpt show: disk0: Pri GPT at sector 1

gpt show: disk0: Sec GPT at sector 488397167

start size index contents

0 1 MBR

1 1 Pri GPT header

2 32 Pri GPT table

34 6

40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B

409640 96092960 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC

96502600 1269536 3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC

97772136 1432

97773568 390623232 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

488396800 335

488397135 32 Sec GPT table

488397167 1 Sec GPT header


Someone cleverer than me out there on a Sunday evening?

Mac Pro, OS X Mountain Lion (10.8.4)

Posted on Aug 11, 2013 6:33 PM

Reply
Question marked as Best reply

Posted on Aug 11, 2013 6:56 PM

may as well output FDISK while I'm at it.


Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

1: EE 1023 254 63 - 1023 254 63 [ 1 - 409639] <Unknown ID>

2: AF 1023 254 63 - 1023 254 63 [ 409640 - 96092960] HFS+

3: AB 1023 254 63 - 1023 254 63 [ 96502600 - 1269536] Darwin Boot

*4: 07 1023 254 63 - 1023 254 63 [ 97773568 - 390623232] HPFS/QNX/AUX

5 replies
Question marked as Best reply

Aug 11, 2013 6:56 PM in response to Random_Tangent

may as well output FDISK while I'm at it.


Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

1: EE 1023 254 63 - 1023 254 63 [ 1 - 409639] <Unknown ID>

2: AF 1023 254 63 - 1023 254 63 [ 409640 - 96092960] HFS+

3: AB 1023 254 63 - 1023 254 63 [ 96502600 - 1269536] Darwin Boot

*4: 07 1023 254 63 - 1023 254 63 [ 97773568 - 390623232] HPFS/QNX/AUX

Aug 17, 2013 1:14 PM in response to Random_Tangent

The two partition tables appear to be synced, so the problem lies elsewhere. Consider booting from the install DVD and running Windows Startup Repair. If that doesn't find anything wrong or fix the problem, then I'd move on to this support documentabout the bootrec.exe tool. You can do this in any order, or all three of them at the same time, but the support document is kinda densely written IMO. You have to click the big

+ Bootrec.exe options

link to reveal the actual options. What's non-obvious is you can either type bootrec.exe and then separately type:


/FixMbr

/FixBoot

/RebuildBcd


Or you can use the vernacaular of 'bootrec <option>' e.g.


bootrec /FixMbr


Also non-obvious is the last ditch effort which is if the above three don't work, do this exactly as documented:

bcdedit /export C:\BCD_Backup

c:

cd boot

attrib bcd -s -h -r

ren c:\boot\bcd bcd.old

bootrec /RebuildBcd

Oct 8, 2013 3:18 PM in response to Random_Tangent

Hi-


I too had a BootCamped install crap out on me when I accidentally shut my computer with windows running. When I pulled it out of my bag, the machine was HOT and would only launch in windows. I reinstalled OSX and see my bootcamp partition but the computer doesn't see it when I option+start.


I have read through pages and pages of the fixes but am not totally clear on how to get it back. I am wondering if someone can help.


Here's the info that seems to be needed. As far as I can see, it should be healthy but I am far from knowledgable.


Thanks for looking!



Last login: Thu Aug 22 14:21:17 on ttys000

myMBP:~ x$

myMBP:~ x$

myMBP:~ x$ sudo gpt -r -vv show disk0

Password:

gpt show: disk0: mediasize=750156374016; sectorsize=512; blocks=1465149168

gpt show: disk0: PMBR at sector 0

gpt show: disk0: Pri GPT at sector 1

gpt show: disk0: Sec GPT at sector 1465149167

start size index contents

0 1 PMBR

1 1 Pri GPT header

2 32 Pri GPT table

34 6

40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B

409640 2008

411648 1070309376 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC

1070721024 1128

1070722152 1269536 3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC

1071991688 1144

1071992832 393148416 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

1465141248 7887

1465149135 32 Sec GPT table

1465149167 1 Sec GPT header





myMBP:~ x$ sudo fdisk /dev/disk0

Disk: /dev/disk0 geometry: 91201/255/63 [1465149168 sectors]

Signature: 0xAA55

Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

1: EE 0 0 1 - 1023 254 63 [ 1 - 1465149167] <Unknown ID>

2: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

3: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused






myMBP:~ x$ diskutil list

/dev/disk0

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *750.2 GB disk0

1: EFI 209.7 MB disk0s1

2: Apple_HFS MACMAIN 548.0 GB disk0s2

3: Apple_Boot Recovery HD 650.0 MB disk0s3

4: Microsoft Basic Data BOOTCAMP 201.3 GB disk0s4

Gregorys-MacBook-Pro:~ greg$

Oct 22, 2013 7:52 PM in response to talitridae

Yes the hybrid MBR has been replaced with a protective MBR, so the hybrid MBR needs to be recreated. The tool I use to do this is GPT fdisk from sourceforge, download and install that. The basic command to get into interactive edit mode is:


sudo gdisk /dev/rdisk0


You'll need to familiarize yourself with navigating the program.


What you're looking for is the recovery menu, and within that menu is an option to create a new hybrid MBR. You want partitions 2 3 4 added to the MBR, and when it asks, you want the EFI GPT partition first in the MBR, so that's a yes. And when it asks for MBR hex code, just hit enter to accept the default value suggested, and when it asks if you should make that partition bootable say no except for the last one, partition 4 which is for BOOTCAMP, you want that one marked bootable.


Write out the new partition maps, and reboot.

Windows 7 Bootcamp MBR has gone AWOL. Any ideas on getting it back?

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