Q: Help - Windows partition has vanished after OSX updates.
Unsure what has happened here, but I can no longer boot to Windows Partition?
Looking at another thread it was suggested to run the following:
mac-mini:~ ianpaine$ diskutil list
/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *1.0 TB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_HFS Macintosh HD 250.8 GB disk0s2
3: Apple_Boot Recovery HD 650.0 MB disk0s3
4: Microsoft Basic Data 251.0 GB disk0s4
mac-mini:~ ianpaine$ diskutil cs list
No CoreStorage logical volume groups found
mac-mini:~ ianpaine$ sudo gpt -vv -r show /dev/disk0
Password:
gpt show: /dev/disk0: mediasize=1000204886016; sectorsize=512; blocks=1953525168
gpt show: /dev/disk0: Suspicious MBR at sector 0
gpt show: /dev/disk0: Pri GPT at sector 1
gpt show: /dev/disk0: Sec GPT at sector 1953525167
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 489833880 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC
490243520 1269536 3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
491513056 971778848
1463291904 490231808 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
1953523712 1423
1953525135 32 Sec GPT table
1953525167 1 Sec GPT header
mac-mini:~ ianpaine$ sudo fdisk /dev/disk0
Disk: /dev/disk0 geometry: 121601/255/63 [1953525168 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 - 489833880] HFS+
3: AB 1023 254 63 - 1023 254 63 [ 490243520 - 1269536] Darwin Boot
4: 0C 1023 254 63 - 1023 254 63 [1463291904 - 490231808] Win95 FAT32L
Mac mini, OS X Yosemite (10.10.3), null
Posted on May 28, 2015 12:03 PM
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. Please notice the '+' sign in step 8.
Rebuild GPT4 using start/end offsets
- Sudo gdisk /dev/rdisk0
- P (print the full list of parts)
- D (delete)
- 4 (part 4)
- N (new part)
- 4 (part 4)
- 491513856 - Start offset in bytes (start point for Bootcamp part)
- +1462009849 (Size offset as opposed to End offset)
- 0700 (Windows part type)
- P (print list of all parts just to see what changes will be made)
- W (Write the new GPT)
- 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.
- Sudo gdisk /dev/disk0
- P (Print list of parts)
- R (Recover)
- O (print current Hybrid MBR)
- H (chooses Hybrid)
- Partitions numbers to be hybridized: 2 3 4
- Y (Good for GRUB question)
- N (part 2 boot flag)
- N (part 3 boot flag)
- Y (part 4 boot flag make NTFS bootable partition)
- O (print current Hybrid MBR)
- W (Write the new MBR)
- Y (Yes! write the new MBR)
- Reboot
Here is sample Q&A for this section. Please notice the Press Enter/Return.
Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): Y
Creating entry for GPT partition #2 (MBR partition #2)
Enter an MBR hex code (default AF): Press Enter/Return
Set the bootable flag? (Y/N): N
Creating entry for GPT partition #3 (MBR partition #3)
Enter an MBR hex code (default AB): Press Enter/Return
Set the bootable flag? (Y/N): N
Creating entry for GPT partition #4 (MBR partition #4)
Enter an MBR hex code (default 07): Press Enter/Return
Set the bootable flag? (Y/N): Y
Test 1 - Does Bootcamp Volume show up in Finder?
Test 2 - Can you see files in Bootcamp Volume?
Test 3 - Can you select Bootcamp in System Preferences -> Startup Disk?
Test 4 - If Test 3 is successful, select Bootcamp and Click Restart.
Posted on May 28, 2015 12:49 PM


