Bootcamp partition is no longer visible and bootable

Question

Level 1

4 points

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 2:33 AM

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Answer 1

gytis90210 Author

Level 1

4 points

Sep 13, 2014 2:36 AM in response to gytis90210

Additional information: before making changes mentioned in the second thread (while i was still able to boot to windows, but I could no longer access it via OS X) gpt looked like this (changes highlighted):

GycioMPB:~ gytis$ sudo gpt -r -vv show disk0

Password:

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 184

533241856 27344896 4

560586752 64555008 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

625141760 655

625142415 32 Sec GPT table

625142447 1 Sec GPT header

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Answer 2

Loner T

Level 9

59,513 points

Sep 14, 2014 7:41 AM in response to gytis90210

Can you post the output of

sudo dd if=/dev/rdisk0s4 count=1 2>/dev/null | hexdump -C

to check if the NTFS header is intact.

Resizing of Bootcamp with a Hybrid MBR is not allowed. See Bootcamp FAQ - Boot Camp 5.1: Frequently asked questions.

More than likely, it may be 533241672 which is the location for it.

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Answer 3

gytis90210 Author

Level 1

4 points

Sep 14, 2014 10:12 AM in response to Loner T

Hi Loner,

please see the output:

00000000 eb 52 90 4e 54 46 53 20 20 20 20 00 02 08 00 00 |.R.NTFS .....|

00000010 00 00 00 00 00 f8 00 00 3f 00 ff 00 00 e0 69 21 |........?.....i!|

00000020 00 00 00 00 80 00 80 00 f8 07 d9 03 00 00 00 00 |................|

00000030 00 00 0c 00 00 00 00 00 02 00 00 00 00 00 00 00 |................|

00000040 f6 00 00 00 01 00 00 00 99 bf 2f fc e2 2f fc d2 |........../../..|

00000050 8c 92 fe 64 fa 33 c0 8e d0 bc 00 7c fb 68 c0 07 |...d.3.....|.h..|

00000060 1f 1e 68 66 00 cb 88 16 0e 00 66 81 3e 03 00 4e |..hf......f.>..N|

00000070 54 46 53 75 15 b4 41 bb aa 55 cd 13 72 0c 81 fb |TFSu..A..U..r...|

00000080 55 aa 75 06 f7 c1 01 00 75 03 e9 dd 00 1e 83 ec |U.u.....u.......|

00000090 18 68 1a 00 b4 48 8a 16 0e 00 8b f4 16 1f cd 13 |.h...H..........|

000000a0 9f 83 c4 18 9e 58 1f 72 e1 3b 06 0b 00 75 db a3 |.....X.r.;...u..|

000000b0 0f 00 c1 2e 0f 00 04 1e 5a 33 db b9 00 20 2b c8 |........Z3... +.|

000000c0 66 ff 06 11 00 03 16 0f 00 8e c2 ff 06 16 00 e8 |f...............|

000000d0 4b 00 2b c8 77 ef b8 00 bb cd 1a 66 23 c0 75 2d |K.+.w......f#.u-|

000000e0 66 81 fb 54 43 50 41 75 24 81 f9 02 01 72 1e 16 |f..TCPAu$....r..|

000000f0 68 07 bb 16 68 70 0e 16 68 09 00 66 53 66 53 66 |h...hp..h..fSfSf|

00000100 55 16 16 16 68 b8 01 66 61 0e 07 cd 1a 33 c0 bf |U...h..fa....3..|

00000110 28 10 b9 d8 0f fc f3 aa e9 5f 01 90 90 66 60 1e |(........_...f`.|

00000120 06 66 a1 11 00 66 03 06 1c 00 1e 66 68 00 00 00 |.f...f.....fh...|

00000130 00 66 50 06 53 68 01 00 68 10 00 b4 42 8a 16 0e |.fP.Sh..h...B...|

00000140 00 16 1f 8b f4 cd 13 66 59 5b 5a 66 59 66 59 1f |.......fY[ZfYfY.|

00000150 0f 82 16 00 66 ff 06 11 00 03 16 0f 00 8e c2 ff |....f...........|

00000160 0e 16 00 75 bc 07 1f 66 61 c3 a0 f8 01 e8 09 00 |...u...fa.......|

00000170 a0 fb 01 e8 03 00 f4 eb fd b4 01 8b f0 ac 3c 00 |..............<.|

00000180 74 09 b4 0e bb 07 00 cd 10 eb f2 c3 0d 0a 41 20 |t.............A |

00000190 64 69 73 6b 20 72 65 61 64 20 65 72 72 6f 72 20 |disk read error |

000001a0 6f 63 63 75 72 72 65 64 00 0d 0a 42 4f 4f 54 4d |occurred...BOOTM|

000001b0 47 52 20 69 73 20 6d 69 73 73 69 6e 67 00 0d 0a |GR is missing...|

000001c0 42 4f 4f 54 4d 47 52 20 69 73 20 63 6f 6d 70 72 |BOOTMGR is compr|

000001d0 65 73 73 65 64 00 0d 0a 50 72 65 73 73 20 43 74 |essed...Press Ct|

000001e0 72 6c 2b 41 6c 74 2b 44 65 6c 20 74 6f 20 72 65 |rl+Alt+Del to re|

000001f0 73 74 61 72 74 0d 0a 00 8c a9 be d6 00 00 55 aa |start.........U.|

00000200

So do you think there are there any chances of fixing it?

Though it is sad that resizing of bootcamp is not supported natively (by Disk Utility?) as it seems a lot of people would like to have this.

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Answer 4

Loner T

Level 9

59,513 points

Sep 14, 2014 10:50 AM in response to gytis90210

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.

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Answer 5

Dr.Mac.

Level 3

650 points

Sep 14, 2014 10:43 AM in response to gytis90210

On NTFS volumes, the data enable Ntldr to find the master file table (MFT) during startup. The MFT is not located in a predefined sector, as on FAT32 volumes. For this reason, the MFT can be moved if there is a bad sector. However, if the data is corrupted, the MFT cannot be located, and Windows assumes that the volume has not been formatted. If the NTFS boot sector is damaged, data cannot be accessed. Windows will prompt The drive is not formatted, do you want to format it now? Linux mount will display wrong fs type, bad option, bad superblock

The following illustrates the proper boot sector of an NTFS volume. Bytes 0x00 0x0A are the jump instruction and the OEM ID (shown in bold print).

00000000: EB 52 90 4E 54 46 53 20 - 20 20 20 00 02 08 00 00 .R.NTFS .....

Your NTFS header seems intact.
00000000 eb 52 90 4e 54 46 53 20 20 20 20 00 02 08 00 00 |.R.NTFS .....|

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Answer 6

Loner T

Level 9

59,513 points

Sep 14, 2014 10:51 AM in response to Dr.Mac.

Much better and precise description , Dr.Mac. Thank you.

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Answer 7

gytis90210 Author

Level 1

4 points

Sep 14, 2014 12:05 PM in response to Loner T

Thanks Loner T for the quick response, and thanks Dr. Mac for detailed explanation.

Regarding b. - gdisk suggests to use 625142414 as the last sector for partition #4 - should I use it, or should I use 625141759, (that was the last sector of deleted #4)?

Last sector (533241856-625142414, default = 625142414) or {+-}size{KMGTP}:

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Answer 8

Loner T

Level 9

59,513 points

Sep 14, 2014 12:15 PM in response to gytis90210

By default, since this the last GPT entry, it wants to set it to a byte before the secondary table. You can use it, because typically it is unused, but the MBR needs to be matched to it. I suggest using the MBR entry, but it is the size, not the end sector, you will need to calculate it. GDisk uses start/end, while MBR uses start/size. 😉

533241856 + 27344896 + 64555008 = 625141760

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Answer 9

gytis90210 Author

Level 1

4 points

Sep 14, 2014 12:55 PM in response to Loner T

After deleting and re-adding partition #4 I am no longer able to see Windows in the list of OS'es (when I hit Alt on booting)

gdisk partitions are displayed like this:

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 844 sectors (422.0 KiB)

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 533241856 625141760 43.8 GiB AF00 Apple HFS/HFS+

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: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

So I assume i should proceed with d. then? Should I do this with gdisk:

r recovery and transformation options (experts only)

g convert GPT into MBR and exit

h make hybrid MBR

w write table to disk and exit

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Answer 10

Loner T

Level 9

59,513 points

Sep 14, 2014 1:04 PM in response to gytis90210

1. Change the partition type to 07 for partition 4 via Gdisk.

2. Use the 'h' option and put 2 3 4 in the hybrid MBR, say yes to include EFI in MBR (the "good for grub" question).

3. Make 4 bootable. Verify the MBR.

4. Verify the Volume in Finder.

5. Verify files in the Bootcamp volume.

6. Test.

The message where you said Windows was bootable not in startup disk, has 533241856.

Testdisk can be used to get valid start/end locations, if necessary, but it is slow process. I have to step away for a couple of hours.

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Answer 11

gytis90210 Author

Level 1

4 points

Sep 14, 2014 1:32 PM in response to Loner T

Thanks, it is all good now - I am able to see my Windows disk in Finder, and I was able to successfully boot into Windows.

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Answer 12

Loner T

Level 9

59,513 points

Sep 14, 2014 1:34 PM in response to gytis90210

Excellent.

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