MacBook – “First Aid found corruption that needs to be repaired”

To recover the Boot Camp partition (Source):

Enter:

sudo gpt -vv -r show /dev/disk0

to get some partition informations.

Download and install GPT Fdisk (aka gdisk).

Download and install TestDisk.

Open TestDisk and make a deep search for your Windows partition.

Leave your Testdisk display and start a new Terminal Window. You need to use the following steps. If you see any error messages during the following steps, please stop and post back here with the error message. The following steps have values from your Testdisk output (and you can verify) in Steps 7 and 8. They should be the same as in the gpt output. Please notice the '+' sign in step 8 (this is called offset notation). The text in parentheses is for informational purpose to describe the action being taken. Gdisk has one-character commands except when entering numbers.

Rebuild GPT4 using start/end offsets

1. sudo gdisk /dev/rdisk0
2. P (print the full list of parts)
3. D (delete)
4. 4 (part 4)
5. N (new part)
6. 4 (part 4)
7. 1564180480 ( - Start offset in blocks or the start point for Bootcamp part)
8. +389343232 ( - Size offset, as opposed to End offset)
9. 0700 (Windows part type)
10. P (print list of all parts just to see what changes will be made)
11. W (Write the new GPT)
12. Y (Yes! really write the new GPT)

This will delete and re-write the GPT partition info for /dev/disk0s4.

Rebuild MBR to match the new GPT information thus resetting the Hybrid MBR. Use defaults for other questions (like partition codes). The only values that need modifications are the Boot flags and step 10. Accept all other defaults that Gdisk offers. These steps can be repeated if you make a mistake before you get to Step 12, otherwise start from Step 1 for these steps. Step 6 has numbers which are typed with a space between the numbers.

1. sudo gdisk /dev/rdisk0
2. P (Print list of parts)
3. R (Recover)
4. O (print current Hybrid MBR)
5. H (chooses Hybrid)
6. Partitions numbers to be hybridized: 2 3 4
7. Y (Good for GRUB question)
8. N (part 2 boot flag) N (part 3 boot flag)
9. Y (part 4 boot flag make NTFS bootable partition)
10. O (print current Hybrid MBR)
11. W (Write the new MBR)
12. Y (Yes! write the new MBR)
13. Reboot

To make Windows bootable again try the following:

Boot from your Windows DVD/USB-Stick

1. Open command prompt from Windows recovery option menu. Type “diskpart” at the command prompt.

2. At the DiskPart prompt, type in “list disk”. You will see the list of disk currently attached to your computer.

3. Now type in “select disk n”, where n is the disk number. In this example, disk 0 is selected.

4. Now that correct disk is selected, type in “list partition” to get a list of all the partitions on that disk.

5. To select the partition you want to set as active, type in “select partition n”, where n is the partition number (probably 3).

6. Now that you have selected the disk and partition, mark it as active by just typing the word “active” and pressing Enter. Now the partition is set active.

7. Exit from the command prompt and run startup repair.

You most probably still have the disk partitioned in the GPT, but there are no partitions on the disk any more. This has happened to me twice when trying to remove the Boot Camp partition.

You have to compare the output of diskutil list disk0 and sudo gpt show disk0 to see which partitions are still in the GPT, but are marked as unused. Then you'll have to create a temporary partition which you can then delete from Disk Utility.

For example,

[onik@Oniks-MacBook-Air ~]$ diskutil list disk0
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *251.0 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                  Apple_HFS Macintosh HD            204.0 GB   disk0s2
   3:         Microsoft Reserved                         16.8 MB    disk0s3
   4:                 Apple_Boot Recovery HD             650.1 MB   disk0s4
onik@Oniks-MacBook-Air ~]$ sudo gpt show disk0
      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  398437504      2  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
  398847144        856         
  398848000      32768      3  GPT part - E3C9E316-0B5C-4DB8-817D-F92DF00215AE
  398880768     228520         
  399109288    1269760      4  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
  400379048   89855676         
  490234719         32         Sec GPT table
  490234751          1         Sec GPT header

shows that there is unused but reserved space at the end of the disk (the line after index 4). You can solve this by creating a partition in the space manually.

Boot into recovery and open a terminal. Unmount the disk with diskutil unmountDisk disk0 (use your own disk number) and calculate the available space for the partition. OSX needs 262144 sectors of empty space after each partition, so subtract that from the size of the space available. After this, create the partition with sudo gpt add -b 400379048 -s 89829462 -t hfs disk0.

After this, if you run diskutil list disk0 again, you'll see the partition, but you'll need to format it. sudo newfs_hfs -v "Temporary volume" -J /dev/rdisk0s5 will do the trick (but use your own disk and partition number). Now you can close the terminal, open up Disk Utility and delete the temporary partition, and Disk Utility will take care of the rest.

Now just reboot and run Boot Camp Assistant again!