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I have a Mac Book Pro with 320GB HDD, I had Mac OSX (139.70 GB) on one partition (using BOOTCAMP) and Windows 7 (157.59GB) on other partition (Bootcamp). And in Windows I divided that single partition in to two, primary partition (with 79.97GB) and remaining as an extended partition. Yesterday I upgraded Mac OSX Lion to new Mac OSX Mountain Lion and it completed successfully, but when I started my system in Windows mode it doesn't showed my extended partition, see the picture below:

enter image description here

As you can see in red mark, it still says 157.59GB but only shows primary partition (see green mark) having 79.97GB so now I am missing that remaining partition. I tried System Restore but there is no restore point and also tried seeing the parition in Safe Mode but no luck. Can anyone tell me what went wrong and what should I do?

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In the picture I see it's reporting 2 different sizes for the NTFS partition, but I don't see anything that's disappeared. Do you mean there used to be another partition after it? – Mechanical snail Jul 27 '12 at 6:04
yes there used to be another partition and besides two different sizes it's not showing any free available space ... – Safran Ali Jul 27 '12 at 8:18
up vote 1 down vote accepted

I suggest you to use TestDisk. TestDisk is powerful free data recovery software! It was primarily designed to help recover lost partitions and/or make non-booting disks bootable again when these symptoms are caused by faulty software, certain types of viruses or human error (such as accidentally deleting a Partition Table). Partition table recovery using TestDisk is really easy.

It can be downloaded from TestDisk Download. Extract the files from the archive including the sub-directories. To recover a lost partition or repair the filesystem from a hard disk, USB key, Smart Card, etc., you need enough rights to access a physical device.

Under MacOSX, if you are not root, TestDisk (ie testdisk-6.13/testdisk) will restart itself using sudo after confirmation on your part.

This TestDisk step by step guides you to recover a missing partition and repair a corrupted one.

Hope it helps.

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The thread Lost bootcamp windows boot option may also address your problem :

Mac OS X often uses a hybrid GPT and MSDOS partition table scheme. These two partition tables can get out-of-sync. When this happens you can use the rEFIt application to re-sync the partition tables. See the GParted FAQ.

Another advice on this thread was to use GPT fdisk to repair damaged GPT data structures or FixParts (same link) to repair damaged MBR data structures.

Whatever you do, you will need to carefully study the partition table. It may even be that recreating the partition in Windows (without formatting) may recover the missing partition, but be prepared for the worse.

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I tried using GPT fdisk and also rEFIt but no progress, I might missing something. Can you please provide a bit more details ... thanks – Safran Ali Jul 31 '12 at 15:47

I have a strong suspicion of what went wrong.

Mac OS X uses a hybrid GPT + MBR, where the GPT is authoritative and the MBR is not. When using a Hybrid GPT + MBR, you need to make sure that every single tool you use that ever edits partition tables knows how to handle Hybrid GPT + MBR setups correctly. I suspect the partition-splitting you did in Windows only updated the MBR, and the OS X Mountain Lion update saw the discrepancy and "fixed" it by overwriting the "corrupt"/"incorrect" MBR with a new copy of the data from the "authoritative" GPT. So it probably wiped out any information about how you'd split that Windows primary partition into a smaller primary plus an extended.

Without knowing exactly which block your post-split, smaller Windows primary partition ended on, and which block your post-split, Windows extended partition started on, there's no way to fix this. Also, even if you did know those block numbers, if you ran any OS that did a read-write mount of that "recombined" or "larger, no longer split" Windows primary partition, and wrote any data to it, there's a chance it could have overwritten the blocks at the beginning of the post-split extended partition, corrupting that volume and wiping out its records of what files are stored where.

One way to fix this (assuming the directory data structures at the start of the extended partition didn't already get stepped on), would be to read up on GPT and MBR table formats and low-level tools, look at what your GPT and MBR looked like before the Mountain Lion upgrade (assuming you have those tables backed up somewhere, which is somewhat unlikely because a lot of backup software backs up files or partitions, but not the entire disk including the partition table sectors), look at what they look like now, and use the low level tools to repair the damage.

If you do have a sufficiently recent (but pre Mountain Lion upgrade) full-disk backup that includes the partition tables, you might be able to fix this without going to low-level, something like this:

  1. Back up any work you've done since the Mountain Lion upgrade.
  2. Test your backups.
  3. Restore your full-disk backup.
  4. Test it to make sure your two split partitions show up again and work correctly and have all their data.
  5. Run a tool to sync your MBR and your GPT, this time taking your MBR as authoritative.
  6. Test it to make sure everything's still fine.
  7. Make a full disk backup again.
  8. Test your backup.
  9. Install Mountain Lion.
  10. Test to make sure the Mountain Lion install didn't lose your split volume this time, or cause any other problem.
  11. Carefully restore the files you backed up in step 1.
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I don't know much technical details about this partition type and I don't think I have backed-up my files while upgrading to Mountain Lion. Is there a way that I can re-claim the missing windows partition space i.e. again create an extended partition as I don't had much data on that but I need that space ... – Safran Ali Aug 4 '12 at 4:47

My guess of what went wrong (but don't have a proven solution), assuming that your initial configuration of partitions was made through something like this.

When you updated to Mountain Lion, it re-installed the recovery partition (see the second line with 620MB in the list of volumes in your screenshot). As long as "You cannot have a disk with more than 4 partitions in Windows 7", the Windows partition disappeared as a result of added OS X Recovery partition.

What I did in a similar situation (after updating from 10.7.5 to 10.8.5) was simply delete the recovery partition, re-create original Windows partition from the scratch and completely restore its contests from the backup. From your comments I already see that this is not an option for you.

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