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How to I fix my Mac startup drive

So I have my computer dual booted with max os Yosemite and Windows 8.1. Today I decided to increase my windows partition. (bad idea I know) I used windows disk manager to do it, and the process went smoothly. Or so I thought. Starting my computer up in windows has no problems, but when I hold the alt/option key to select Mac OS X It wont appear, but the Mac recovery partition does. So I use the recovery partition to open Disk Utility and it says that the partition that mac is installed to is ms dos, but in windows Disk manager it says it is HFS just like the recovery partition. So my question is, why does mac think it is ms dos and how do I make it bootable again without losing Windows? I also don't want to resort to re installing mac osx and losing all my stuff.

Mac mini, OS X Yosemite (10.10.3)

Posted on Apr 30, 2015 8:39 PM

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68 replies

May 1, 2015 1:37 AM in response to cydget

First of all, I am apologize to this thread opener for post my similar problem like him ( cause even I don't know how to open a new thread ), I am a new MacBook user and new in this apple support forum.


01. I got a gift (MacBook Pro Retina 2013 earlier model i7 CPU 750GB SSD and 16GB RAM). few days ago. it was not install any OS X, when I power on, it was show recovery screen and Disk utilities and option to install Mountain Lion OS X.

02. Then I search on google and find way to install (Yosemite 10.10) OS X by bootable USB disk. then my uncle have a MacBook pro from his MacBook pro I make a Yosemite 10.10 OS X bootable USB disk for install OS X. According to google search tutorials I did all and finally I installed ( Yosemite 10.10 ) on my MacBook Pro Retina. I was very happy that World best Laptop I have now with high configuration...!

May 1, 2015 3:01 AM in response to agun21st

First of all, I am apologize to this thread opener for post my similar problem like him ( cause even I don't know how to open a new thread ), I am a new MacBook user and new in this apple support community.


01. I got a gift (MacBook Pro Retina 2013 earlier model i7 CPU 750GB SSD and 16GB RAM). few days ago. it was not install any OS X, when I power on, it was show recovery screen and Disk utilities and option to install Mountain Lion OS X.

02. Then I search on google and find way to install (Yosemite 10.10) OS X by bootable USB disk. then my uncle have a MacBook pro from his MacBook pro I make a Yosemite 10.10 OS X bootable USB disk for install OS X. According to google search tutorials I did all and finally I installed ( Yosemite 10.10 ) on my MacBook Pro Retina and Update it Yosemite 10.10.3. I was very happy that World best Laptop I have now with high configuration...!

03. But when I know that, Apple give chance to install "Windows" in MacBook Pro then I was also more happy that, I am a Java learner and in windows can test my application and SQL server etc. then I am googling and found about BootCamp. then I followed Bootcamp process from my MacBook Pro Retina and make a windows 8.1 x64 bootable disk and installed windows 8.1 Pro Properly. And installed all the Bootcamp drivers for my Windows that was downloaded from internet Bootcamp software during making Bootcamp windows USB disk.

04. Everything was fine, Suddenly I thought that, if Windows OS is being Virus effected or need to reinstall then my all file will be lost from Windows partition...!

Then I decided that, I should "srink partition" for make a Drive that I can put my Documents, as like as Windows Laptop. My Bootcamp drive was 250GB, I try to Shrink Partition 100GB, " Then it was give me a Warning that, something like Boot Problem or something like that. But I thought it is a Normal Warning...! then I Press Yes. and it was Srink and make a 100GB Partition from Device Manager and I format that Partition. "

05. After that I saw some other Partition also showing now on my Windows My Computer Window. Like C,D,E,F. only C and D drive showing Memory space. Then I afraid and Delete that Partition which I made from Device Manager. and in C drive I Extend Volume, now my Windows Volume showed about 250GB.

06. After This foolish think done, I restarted my Windows and see now Default Boot was OS X. but not boot from that, and come Windows 8.1 Starter Screen and showing error Windows boot Screen and restart again and come windows Logo " Preparing Automatic Repair " and after show " Diagnosing your PC " then "Automatic Repair", " Your PC did not start correctly ". two Option showing " Restart " and " Advanced options". from Advanced option I choice Fix windows starting problem and my Windows come on in normal mode but if I Restart my Windows again it show "Preparing Automatic Repair". but My OS X would not boot any more.

07. After again Googling I saw several solution, But when I turn off my MacBook pro and Press and hold cmd+R it show now " Starting Internet Recovery. This may take a while ".

08. Then I tried to Boot from my USB Bootable Yosemite 10.10 OS X by Pressing Option/alt key, it show " Windows" , " Install OS X Yosemite". then I click on OS X Yosemite and boot it from USB. it show Screen " To set up the installation of OS X, Click Continue " But do not want to Loose my Documents and All my Movie collections in mac OS X partition saved in " My Documents ".

09. Then From OS X Installer Screen it show also "Utilities" option and choose "Disk Utility...". and showing now " 751.28 GB APPLE SSD... > disk0s1, disk0s2, disk0s3 "

When I click on " disk0s1 " it show, > Mount Point : Not mounted. > Partition : Windows_LDM. > Capacity : 521.28 GB ( this is my OS X Partition).

and Under APPLE SSD... there are two disk showing Orange drive " disk2>OS X Install ESD " and " disk3>OS X Base System ".

10. Finally Sorry for long history, Please I need help for my MacBook Pro Retina OS X Boot Partition return and save my all Documents in my OS X Partition and Work fine as work before.

"Advance Honor to the community"

May 1, 2015 3:23 AM in response to agun21st

1. You can start a new discussion by submitting a question to the community.

2. You cannot grow or shrink Windows partition on a Mac using tools provided by Apple. You may be able to use third-party tools like Winclone or Camptune.

3. Did you set up Time Machine backups and back up the OS X side before Windows was installed?


09. Then From OS X Installer Screen it show also "Utilities" option and choose "Disk Utility...". and showing now " 751.28 GB APPLE SSD... > disk0s1, disk0s2, disk0s3 "

When I click on " disk0s1 " it show, > Mount Point : Not mounted. > Partition : Windows_LDM. > Capacity : 521.28 GB ( this is my OS X Partition).

and Under APPLE SSD... there are two disk showing Orange drive " disk2>OS X Install ESD " and " disk3>OS X Base System ".


This is normal. Your shrinking/repartitioning also included manipulating OS X partition from Windows side. The "orange' disks are your USB external disk with Yosemite Installer and the OS X base system.


Please see OS X: Installing OS X on an external volume - Apple Support and install OS X on an external disk. Boot from this external disk.


Can you post the output of the following Terminal 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.

May 1, 2015 6:06 AM in response to Loner T

User uploaded fileUser uploaded fileUser uploaded file


"3. Did you set up Time Machine backups and back up the OS X side before Windows was installed?" No sir, I did't do any Time Machine backups before windows.

" Please see OS X: Installing OS X on an external volume - Apple Support and install OS X on an external disk. Boot from this external disk. "

if I install OS X on an external disk, and boot from that then I can see my file in my previous OS X My Documents? or how can I repair OS X drive?

Can you post the output of the following Terminal 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.


I tried this code from Boot Yosemite usb installation I give pictures above.

Sir, Can You give me step by step process that I can enter my OS X My Documents. or Step by Step Process to come back OS X in Normal process without loosing my Files? ( My windows Partition is Working fine. I can access my windows )

I am waiting for hearing from you.

May 1, 2015 3:32 PM in response to agun21st

So here are the images from terminal. http://s000.tinyupload.com/index.php?file_id=56832153295034917368 Sorry about not being able to upload the photos directly, but they were more then 2 Mb. I did not use time machine to back up my drive. I did however create an image of the mac partition using the command dd on a linux live cd. Do you think I should just reinstall mac os x and copy my important files from the hard drive backup image back over, or is there a fast/ easy fix?

May 1, 2015 3:41 PM in response to cydget

cydget wrote:


Do you think I should just reinstall mac os x and copy my important files from the hard drive backup image back over, or is there a fast/ easy fix?

No. Please do not. This is easily fixable. It is just a PartitionType GUID which is incorrect. Please download http://sourceforge.net/projects/gptfdisk/ . Does your Windows boot properly? This can be fixed from either OS.

May 1, 2015 3:45 PM in response to agun21st

agun21st wrote:



now I should do what sir?


" need to install OSX on an external disk based on the link I provided and then boot from it "

do this? or what the second step?

Your issue may also be fixable using GPT Fdisk, since your last screen shot shows a corrupted GPT. Please downloadhttp://sourceforge.net/projects/gptfdisk/ .


Since there are two posters on this discussion, I will quote each person's post so it is clear who it is meant for.

May 1, 2015 6:38 PM in response to agun21st

agun21st wrote:

I am here now... what should Next?

Say 'N here. You do not want to use README.windows as device name. 😉 You want to enter "0:" without the quotes (that is the digit zero and ':'). Press 'p' to print the GPT.


You can use http://windows.microsoft.com/en-us/windows7/products/features/snipping-tool to take screen shots and post. Using a camera is a bit more tedious.

How to I fix my Mac startup drive

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