Mac drive no longer showing up as boot option?

Question

Level 1

8 points

Mac drive no longer showing up as boot option?

MacBook pro 2015. Have bootcamp, mac osx el capitan one side, windows 10 the other. Wanted to make the windows 10 one bigger, used disk utility to shrink mac osx partition. This named the unallocated space 'untitled' wouldn't let me make bootcamp partition bigger. So I switched to windows and tried using Ease US partition master, wouldn't let me resize bootcamp partition either. So (using ease us) deleted 'untitled partition' that was created when I shrunk the mac osx one on mac disk utitlity. Still wouldn't let me resize bootcamp partition. So I created a small partition as NTFS over the now unallocated space, so I could use it for more storage on windows 10. Now when I start the PC no boot option available only Windows 10. Boot camp still running in windows, and I tried clicking restart into Mac OSX, black screen for 10 seconds then boots into windows. Pressing alt when turning on works, but again only windows disk is displayed. I didn't damgage the OSX partition, all I did was make it slightly smaller, (it had a lot of free space). What do I do?

MacBook Pro, OS X El Capitan (10.11)

Posted on Oct 11, 2015 12:07 PM

Reply

Answer 1

Loner T

Level 9

59,471 points

Oct 11, 2015 2:11 PM in response to bensparkes98

Please do not try again, what you did. 😉. It may be possible to recover Windows, but no guarantees. The worst case scenario is you lose Windows.

Please post the output of the following commands.

diskutil list

diskutil cs list

sudo gpt -vv -r show /dev/disk0

sudo fdisk /dev/disk0

The "sudo" commands will prompt for your password, and it will not be echoed back. You may also see a warning about improper use of "sudo" and potential data loss due to "abuse" of the command.

Reply

Answer 2

bensparkes98 Author

Level 1

8 points

Oct 12, 2015 2:17 PM in response to Loner T

Enter these commands where?

Reply

Answer 3

Loner T

Level 9

59,471 points

Oct 12, 2015 2:20 PM in response to bensparkes98

Applications -> Utilities -> Terminal.

Reply

Answer 4

bensparkes98 Author

Level 1

8 points

Oct 12, 2015 2:34 PM in response to Loner T

I don't think you understand my problem. I cant boot into Mac OSX!! I am stuck with only windows after resizing the mac partition. Its still there, but I cant boot to it. Only windows!

Reply

Answer 5

Loner T

Level 9

59,471 points

Oct 12, 2015 2:44 PM in response to bensparkes98

Please download GPT Fdisk from http://sourceforge.net/projects/gptfdisk/ to your Windows side.

You can run Gdisk on the Windows side in a CMD Window with Admin rights as shown in the example below.

Another option you have is to install OS X on an external disk and boot from it - How to install OS X on an external drive connected to your Mac - Apple Support

The last option is to use Target Disk Mode (if you have a second Mac) - Share files between two computers with target disk mode - Apple Support , but this requires cables to be able to connect two Macs using appropriate connectors.

Reply

Answer 6

bensparkes98 Author

Level 1

8 points

Oct 12, 2015 4:47 PM in response to Loner T

GPT Fdisk how do I use this?

Reply

Answer 7

Loner T

Level 9

59,471 points

Oct 12, 2015 5:17 PM in response to bensparkes98

I downloaded GPT Fdisk to Downloads and expended it. You can see the directory listing in the top window. Start a CMD window with Admin privileges and change directory to the location of Gdisk.

You can either use Gdisk32 or Gdisk64 executable. '0:' indicates disk0.

Type gdisk32.exe 0:

Type p

Type q

Post the output.

Reply

Answer 8

bensparkes98 Author

Level 1

8 points

Oct 14, 2015 12:52 AM in response to Loner T

When I open it, this is all I see....

Reply

Answer 9

Loner T

Level 9

59,471 points

Oct 14, 2015 3:18 AM in response to bensparkes98

Type "0:" (zero colon) without quotes and press Enter/Return. "0:" is the equivalent of disk0 on the Mac side.

Reply

Answer 10

bensparkes98 Author

Level 1

8 points

Oct 14, 2015 11:56 AM in response to Loner T

308.3GB is my mac partition
121.1GB is my Windows
35.7GB Is the bit I cut off the free space on my Mac OSX partition to make a drive I could use for space on the windows side.

Reply

Answer 11

Loner T

Level 9

59,471 points

Oct 14, 2015 12:02 PM in response to bensparkes98

Go to Recovery menu - r

Print MBR - o

Post the output.

Reply

Answer 12

bensparkes98 Author

Level 1

8 points

Oct 14, 2015 12:41 PM in response to Loner T

Reply

Answer 13

Loner T

Level 9

59,471 points

Oct 14, 2015 1:07 PM in response to bensparkes98

Use the Gdisk commands in single quotes without the actual single quotes.

Go To Main Menu - 'm'

Change partition type - 't'

Partition number - 2

HFS - 'AF00'

Change partition type - 't'

Partition number - 3

Apple Boot - 'AB00'

Change partition type - 't'

Partition number - 5

NTFS - '0700'

Print - 'p'

Write - 'w'

Confirm - 'y'

Reboot and test.

Example of a working one is

Command (? for help): p

Disk /dev/disk0: 1954210120 sectors, 931.8 GiB

Logical sector size: 512 bytes

Disk identifier (GUID): 6ED0C429-00D1-4759-B50E-04B6FB80D0E3

Partition table holds up to 128 entries

First usable sector is 34, last usable sector is 1954210086

Partitions will be aligned on 8-sector boundaries

Total free space is 2013 sectors (1006.5 KiB)

Number Start (sector) End (sector) Size Code Name

1 40 409639 200.0 MiB EF00 EFI System Partition

2 409640 1449034287 690.8 GiB AF00 Customer

3 1449034288 1450303823 619.9 MiB AB00 Recovery HD

4 1450305536 1954209791 240.3 GiB 0700 BOOTCAMP

Reply

Answer 14

bensparkes98 Author

Level 1

8 points

Oct 14, 2015 1:24 PM in response to Loner T

Mac OSX now reappeared as a boot option when holding down the alt key on the boot screen. Got to the login screen, no problems. Typed in password, and started loading desktop, then suddenly this:

Reply

Answer 15

Loner T

Level 9

59,471 points

Oct 14, 2015 2:39 PM in response to bensparkes98

Can you boot in Local Recovery (Command+R). If you see a spinning globe then your Local Recovery is corrupted. It is possible that some OS X files are also corrupted. Can use use OS X Safe Mode - Try safe mode if your Mac doesn't finish starting up - Apple Support ?

Reply