Q: Bootcamp partition disappeared after OSX partition resize - how to repair?

First off I don't know what you mean by you've done this with Disk Utility before, because that doesn't make sense. OS X doesn't come with tools to resize NTFS volumes at all. It can't even create them. While it lets you resize OS X volumes, when this creates a 5th partition this is arguably a bug that Disk Utility shouldn't allow because when a 5th partition is created, diskutil removes the hybrid MBR that's required to boot Windows, and replaces it with a protective MBR (a single entry MBR) which makes Windows effectively invisible to the EFI CSM (the BIOS emulator).

I don't know the sequence of events, but there's also some evidence that the start sector in the resulting partitions is made incorrect by something, I don't know what. But even when changing the partition type code to the correct one, the Windows volume still isn't available and Windows still won't boot implying that the partition entry for Windows is wrong. If I'm right, that's a separate bug but that's been much harder to reproduce and track down what's doing it.

So the short version is, you can try fdisk to change the partition type code in the MBR. Both your MBR and GPT have the same values for the Windows volume so there's no way to 2nd guess this.

sudo fdisk -e /dev/disk0   [puts you in interactive edit mode]

setpid 4

07

print   [print the partition map, confirm partition 4 is 07 and has an asterisk]

write

y

Now reboot and see if Windows is visible and bootable. If not, you're in testdisk territory.

So the problem with shrinking in OS X with Lion and Mountain Lion is that in so doing, it creates a 5th partition which renders Windows unbootable. What you propose was possible with 10.6.x since it lacked a Recovery HD partition, therefore shrinking the OS X volume created a 4th partition, which caused the hybrid MBR to survive. Thus Windows was still bootable. The problem though, is that Windows only recognized the MBR, and upon resizing the Windows NTFS volume, it only updates the MBR, not the GPT. So while it works, it breaks the ability of OS X to read the Windows volume, and significantly risks a later utility trying to sync the GPT and MBR which usually means the GPT is used as the trusted source, overwriting the MBR. Since the GPT contains stale information, a sync not only breaks Windows, but its start sector is lost, which then puts you into data recovery territory.

So basically, Apple provides no tools to do this correctly, and neither does Microsoft. You have to use a 3rd party utility that's expressly designed for managing "Boot Camped" drives.

Reboot to OS X and see if it finds the Windows volume. OS X has read only NTFS support built in, so a volume named BOOTCAMP should appear (unless it was renamed to something else at some point). If it's not found, then the start value in the MBR and GPT is probably wrong and you'll need to use testdisk.

If OS X mounts it read only, then the NTFS volume is intact, it just needs its boot loaders fixed which can be done from Windows Startup Repair.

The partition map is supposed to definitively define the start and end sectors of a partition inside which a volume resides, and the superblocks for that volume are located in known offsets from the start and end points.

Testdisk works by essentially ignoring the partition map (because the only reason you'd use it is if you suspect the partition map is wrong) and looks for all superblocks for various file systems and then reports possible volumes. Old superblocks should be marked as invalid but they aren't erased when you resize a file system. So what's happening is, it's finding a combination of invalid, stale, and plausibly good file systems on the disk. It's not indicating a problem.

Anyway, if you have all of the data you want recovered, you're done with testdisk.

Next is how to use the two large partitions you have (one if free space, one is the old broken Windows volume) as a single new Windows volume. If you're happy with the size you've allocated between OS X and Windows, then you could give Disk Utility a shot. It should let you delete the stale Windows partition, and then create a single new MS-DOS volume from all remaining free space. Then you boot the Windows installer, make sure you go into the advanced section when choosing disks to install to, and reformat this volume (as NTFS), then install.

However, I find gdisk significantly more reliable and transparent about what's actually going on than Disk Utility. But it's a command line only utility, which may not be up your alley. It does offer an interactive mode though, so it's readily navigable. The main things to do: delete the Windows partition, create a new partition with default start and end sectors to use all free space, set the partition type code to 0700, and create a hybrid MBR adding partitions 2 3 4 to it. Then write this out to disk. Then run the Windows installer, making sure you reformat that 4th partition first, and installing to it.

The other thing worth mentioning is that I find Boot Camp to be a total PITA for all the problems you've just had with it, and many, many other users. So I suggest if you can, to use a virtual machine instead and just keep one large OS X partition only. Windows then exists in growable disk image file on the OS X volume. If you use Time Machine you'll want to exclude this file from regular backups, as if even one bit changes (which it will just by booting the VM) the whole disk image is considered changed and will be backed up again. One way around this is to use the virtual machine snapshotting feature. The large disk image gets backed up once because it never changes, only the snapshot file changes from that point onward, and is a much smaller file to backup every hour (or whatever).

I've also had this particular problem crop up, and managed to fix the de-synchronised partition tables using a bootloader called rEFIt, as per this post:

http://forums.macrumors.com/showpost.php?p=16925896&postcount=17

You might find it useful in your case.

I just lost access to my Windows 7 Bootcamp partition after decreasing the size of my mac partition. I did successfully changed the partition sizes once a few weeks ago. I have studied some of the threads but this is over my head to try to fix myself and I would appreciate any help! Thanks!

MacBook-Pro:~ slvrmbpro$ sudo fdisk /dev/disk0
Password:
Disk: /dev/disk0    geometry: 91201/255/63 [1465149168 sectors]
Signature: 0xAA55
  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 - 1318359368] HFS+       
3: AB 1023 254  63 - 1023 254  63 [1318769008 -    1269536] Darwin Boot
4: 0C 1023 254  63 - 1023 254  63 [1396791296 - 68356096] Win95 FAT32L

MacBook-Pro:~ slvrmbpro$ sudo gpt -r -vv show disk0
gpt show: disk0: mediasize=750156374016; sectorsize=512; blocks=1465149168
gpt show: disk0: Suspicious MBR 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         MBR
  1 1         Pri GPT header
  2 32         Pri GPT table
  34 6        
  40      409600      1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
409640 1318359368      2  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
1318769008     1269536 3  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
1320038544 76752752        
1396791296    68356096 4  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
1465147392        1743
1465149135 32         Sec GPT table
1465149167 1         Sec GPT header