Q: Bootcamp partition is no longer visible and bootable
I decided to change size of my bootcamp (windows partition) by following steps in this thread:
how to resize my bootcamp partition without deleting itit
I ended up with having bigger windows partition (which is what I was trying to achieve), that I was able to boot to, but my Windows disk was no longer seen in OS X. I reviewed the thread above once again and it was pointing to another thread where folks were discussing issue similar to mine:
Repairing Boot Camp after creating new partition
Bottom line - Unfortunately, after performing the suggested action plan, I am no longer able to boot to my windows partition nor to see it from OS X
(I am able to select Windows disk while hitting Alt/Option during the boot, but then I get the message 'A Disk Read Error Occured. Press CTRL+ALT+DEL to restart')
Please see the diagnostics below and please advise how this could be fixed - at minimum I would like to boot to Windows partition again, maximum - also to access it via OSX as well.
GycioMPB:~ gytis$ sudo gpt -r -vv show disk0
gpt show: disk0: mediasize=320072933376; sectorsize=512; blocks=625142448
gpt show: disk0: Suspicious MBR at sector 0
gpt show: disk0: Pri GPT at sector 1
gpt show: disk0: Sec GPT at sector 625142447
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 531562496 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC
531972136 1269536 3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
533241672 27345080
560586752 64555008 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
625141760 655
625142415 32 Sec GPT table
625142447 1 Sec GPT header
GycioMPB:~ gytis$ sudo fdisk /dev/disk0
Disk: /dev/disk0 geometry: 38913/255/63 [625142448 sectors]
Signature: 0xAA55
Starting Ending
#: id cyl hd sec - cyl hd sec [ start - size]
------------------------------------------------------------------------
1: EE 0 0 2 - 25 127 14 [ 1 - 409639] <Unknown ID>
2: AF 25 127 15 - 1023 254 63 [ 409640 - 531562496] HFS+
3: AB 1023 254 63 - 1023 254 63 [ 531972136 - 1269536] Darwin Boot
*4: 07 1023 254 63 - 1023 254 63 [ 560586752 - 64555008] HPFS/QNX/AUX
GycioMPB:~ gytis$ sudo gdisk /dev/disk0
GPT fdisk (gdisk) version 0.8.10
Warning: Devices opened with shared lock will not have their
partition table automatically reloaded!
Partition table scan:
MBR: hybrid
BSD: not present
APM: not present
GPT: present
Found valid GPT with hybrid MBR; using GPT.
Command (? for help): p
Disk /dev/disk0: 625142448 sectors, 298.1 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): 000066EB-7670-0000-C052-0000E7240000
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 625142414
Partitions will be aligned on 8-sector boundaries
Total free space is 27345741 sectors (13.0 GiB)
Number Start (sector) End (sector) Size Code Name
1 40 409639 200.0 MiB EF00 EFI system partition
2 409640 531972135 253.5 GiB AF00 Customer
3 531972136 533241671 619.9 MiB AB00 Recovery HD
4 560586752 625141759 30.8 GiB 0700 Win HD
Command (? for help):
Thanks!
MacBook Pro (15-inch Mid 2010), OS X Mavericks (10.9.4)
Posted on Sep 13, 2014 2:39 AM
1. Excellent that the NTFS header is intact. This should be fixable. I assume that you have a TM backup of OSX, if necessary.
2. This an oversimplified explanation, but older Macs which do not implement the Intel UEFI specification (pre-EFI 2.0) and stay with EFI 1.1, that Macs have used till 2013, cannot use Windows UEFI installation properly. Windows 7 also has some issues with UEFI (mainly drivers) on Macs. Late 2013 Macs have UEFI support, so it is possible to install Windows 8+ via UEFI, which means your disk is a pure GPT disk (unlike the Bootcamp Hybrid MBR implementation). Disk Utility can then be used to resize GPT partitions, because Windows 8.1 (for example) uses a FAT Microsoft System Reserved partition in conjunction with the Microsoft Basic Data partition, which allows resizing. DU also understands MBRs, but should ensure that MBR and GPT stay in sync, which is not implemented. Windows can resize the MBRs, but fails to update the GPT (because it is unaware of such a Hybrid MBR), and then you have this issue.
3. Using Gdisk...
a. Delete GPT#4.
b. Add GPT# 4 back, with the start at 533241856.
c. Test 1 - Mount Bootcamp and verify that it will mount.
Test 2 - Make sure you can see files.
Test 3 - Make sure you can see Bootcamp in Startup Disk.
Test 4 - Switch to Windows. This may also need Windows startup repair.
d. Recreate Hybrid MBR, if necessary if Test 4 fails. These two should stay in sync.
e. This can also be tested using Testdisk.
Posted on Sep 14, 2014 10:50 AM