Lost Mac partitions unassignable in Bootcamp

Question

LIZEREIKE Author

Level 1

8 points

Lost Mac partitions unassignable in Bootcamp

iMac mid 2010

Sierra10.12 Windows10

Samsung SSD500Gb(Macintosh HD & bootcamp) + original HDD 1Tb(win storage & Mac storage)

Hi there~

First of all, I'm chinese, so it might be a little hard to understand what I'm saying, thx for ur patient~

I asked this question on a chinese Mac communities this afternoon and soon I get replies like this:

'Congratulations! it's forbidden to fix windows mbr on Mac. Wipe your entire disk and reinstall Mac and windows'

'Why u even monkeying around'

'Just reinstall bootcamp'

And then my post was deleted by that forum later...

I was like....yeah right, why am I so stupid to believe that I can get an answer from those who solve all problems only by reinstall OS...

So here I come, hope someone can help me out.

A few days ago I plugged my external HDD which has two partitions to windows, it shows two partitions twice on the left side of the file explorer, both as local drive(where Macintosh HD and Mac storage should be) and external drive, and those two Mac partitions just disappeared....

I thought it was due to windows can't read hfs partition, so I installed HFS+ for windows and it asked to restart so I hit ok

then booooom! after first black screen there's only 'NO OS' showed on the screen

After bootsec rewriting mbr, chkdsk, reboot in safe mode and disabled Gcard driver, solved NO OS/missing operating system/inaccesable boot device problems and finally back to normal windows, I still can't find my Mac partitions......

Boot with option key shows all three bootable device

I can see all partitions in Computer Management in windows, but I just can't assign letter to the missing partitions, the right click menu is all grey except delete partition

I can use Mac system normally and all 4 partitions are fine

So it seems there's something wrong with windows's partition table. Can I repair/reset/manually rebuild windows partition table with diskutil on Mac?

iMac, macOS Sierra (10.12), mid 2010

Posted on Oct 12, 2016 7:11 AM

Reply

Answer 1

Loner T

Level 9

59,536 points

Oct 12, 2016 7:34 AM in response to LIZEREIKE

From OSX, please post the output of

diskutil list

diskutil cs list

Reply

Answer 2

LIZEREIKE Author

Level 1

8 points

Oct 12, 2016 7:47 AM in response to Loner T

/dev/disk0 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *500.1 GB disk0

1: EFI EFI 209.7 MB disk0s1

2: Apple_HFS Macintosh HD 249.2 GB disk0s2

3: Apple_Boot Recovery HD 650.0 MB disk0s3

4: Microsoft Basic Data BOOTCAMP 250.0 GB disk0s4

/dev/disk1 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *1.0 TB disk1

1: EFI EFI 209.7 MB disk1s1

2: Apple_HFS Mac Storage 499.9 GB disk1s2

3: Microsoft Basic Data Win Storage 499.9 GB disk1s3

No CoreStorage logical volume groups found

Reply

Answer 3

Loner T

Level 9

59,536 points

Oct 12, 2016 7:57 AM in response to LIZEREIKE

Please post the output of

sudo gpt -vv -r show /dev/disk0

sudo fdisk /dev/disk0

I suggest removing any third-party HFS+ drivers from the Windows side, so we can diagnose this further.

Reply

Answer 4

LIZEREIKE Author

Level 1

8 points

Oct 12, 2016 8:08 AM in response to Loner T

gpt show: /dev/disk0: mediasize=500107862016; sectorsize=512; blocks=976773168

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 976773167

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 486812704 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC

487222344 1269536 3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC

488491880 1176

488493056 488280064 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

976773120 15

976773135 32 Sec GPT table

976773167 1 Sec GPT header

Disk: /dev/disk0 geometry: 60801/255/63 [976773168 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 25 127 15 - 1023 254 63 [ 409640 - 486812704] HFS+

3: AB 1023 254 63 - 1023 254 63 [ 487222344 - 1269536] Darwin Boot

*4: 0C 1023 254 63 - 1023 254 63 [ 488493056 - 488280064] Win95 FAT32L

I forgot to mention it, I just installed macdrive10 to see if I can find Mac partitions back, and again, it causes reboot into 'inaccessible boot device' screen....... I'll try to remove it in Parallels or Win safe mode....

please go on and thank u for ur advice~

Reply

Answer 5

Loner T

Level 9

59,536 points

Oct 12, 2016 8:14 AM in response to LIZEREIKE

OSX has a built-in NTFS driver/KEXT (default is read-only). Windows 10 (1511 ISO) uses BC6 JHFS+ driver for read-only access.

Unless you need to read-write, you do not need any third-party drivers. They conflict with the Apple supplied drivers.

Please be aware that a 2010 iMac does not officially support W10, so you may have driver issues. W10 (1607 ISO) and Anniversary Update break the Windows Apple JHFS+ driver.

Reply

Answer 6

LIZEREIKE Author

Level 1

8 points

Oct 12, 2016 9:10 AM in response to Loner T

Not supposed to read-write on Mac in win, I just thought that I can use HFS+ to find Mac partitions back but turned out to be a much more complicate mess

I remember the first time I updated windows from 7to 8, bootcamp manager can't reboot to Mac if I right click on it and choose reboot in Macintosh HD. There will be a pop up window shows 'unable to find Macintosh HD'. I have to open bootcamp control panel, select boot device to get into Mac OS.

And I have to fix brightness/ volume adjustment no respond bug by searching solutions on google.

Purchased the latest magic keyboard few months ago, it worked well on OSX but Fn key is not functional while using Win10 so the function keys on top are useless again... I don't usually use those keys so it's ok to me.

Think it's time for me to have a new iMac 🙂

So, is there any hope I can fix the mbr problem n make Mac partitions show up again? Cause I don't wanna solve those reinstall issues one more time

Regards

Reply

Answer 7

Loner T

Level 9

59,536 points

Oct 12, 2016 9:21 AM in response to LIZEREIKE

Your MBR on disk0 is fine. There is no need to fix it.

Can you post the GPT and Fdisk command output for disk1?

Reply

Answer 8

LIZEREIKE Author

Level 1

8 points

Oct 12, 2016 9:26 AM in response to Loner T

Sure~

gpt show: /dev/disk1: mediasize=1000204886016; sectorsize=512; blocks=1953525168

gpt show: /dev/disk1: Suspicious MBR at sector 0

gpt show: /dev/disk1: MBR at sector 976836608

gpt show: /dev/disk1: Pri GPT at sector 1

gpt show: /dev/disk1: 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 976426672 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC

976836312 296

976836608 1 Extended MBR

976836609 2047

976838656 260096 1 Extended MBR part 7

977098752 976424960 3 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

1953523712 1423

1953525135 32 Sec GPT table

1953525167 1 Sec GPT header

Disk: /dev/disk1 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 25 127 15 - 1023 254 63 [ 409640 - 976426672] HFS+

3: 0F 1023 254 63 - 1023 254 63 [ 976836608 - 262144] Extended LBA

4: 07 1023 254 63 - 1023 254 63 [ 977098752 - 976424960] HPFS/QNX/AUX

Signature: 0xAA55

Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

1: 07 0 32 33 - 16 81 1 [ 976838656 - 260096] HPFS/QNX/AUX

2: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

3: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

Reply

Answer 9

Loner T

Level 9

59,536 points

Oct 12, 2016 9:38 AM in response to LIZEREIKE

LIZEREIKE wrote:

Sure~

gpt show: /dev/disk1: mediasize=1000204886016; sectorsize=512; blocks=1953525168

gpt show: /dev/disk1: Suspicious MBR at sector 0

gpt show: /dev/disk1: MBR at sector 976836608

gpt show: /dev/disk1: Pri GPT at sector 1

gpt show: /dev/disk1: 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 976426672 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC

976836312 296

976836608 1 Extended MBR

976836609 2047

976838656 260096 1 Extended MBR part 7

977098752 976424960 3 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

1953523712 1423

1953525135 32 Sec GPT table

1953525167 1 Sec GPT header

Can you explain why there is an Extended MBR and Extended MBR Part 7 on this disk? What tools we're used to create these? Was Windows Disk Management used on this disk?

You only need the following entries and a matching MBR.

gpt show: /dev/disk1: mediasize=1000204886016; sectorsize=512; blocks=1953525168

gpt show: /dev/disk1: Suspicious MBR at sector 0

gpt show: /dev/disk1: MBR at sector 976836608

gpt show: /dev/disk1: Pri GPT at sector 1

gpt show: /dev/disk1: 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 976426672 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC

977098752 976424960 3 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

1953523712 1423

1953525135 32 Sec GPT table

1953525167 1 Sec GPT header

This will allow read-write to GPT2 (JHFS+) from OSX and read-write to GPT3 from Windows.

Reply

Answer 10

LIZEREIKE Author

Level 1

8 points

Oct 15, 2016 4:38 AM in response to Loner T

That part 7 was unused space, so i made a test on that part to see if i can assign letter. after that i delete its letter so it shows as Newdisk now.

Now that the mbr is ok, what else will causes windows unable to read HFS partiton?

Reply

Answer 11

Loner T

Level 9

59,536 points

Oct 15, 2016 10:33 AM in response to LIZEREIKE

W10 breaks the Apple JHFS+ driver supplied by Apple. Please see Re: Windows 10 Anniversary + Boot Camp = no longer mounting Mac partition for a detailed discussion.

Reply

Answer 12

Loner T

Level 9

59,536 points

Oct 15, 2016 10:43 AM in response to Loner T

The ISO which 1511_2 as the name does work with these drivers. Once you upgrade to 1607 or Anniversary Update, it breaks.

Reply