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I have a MacBook Pro Retina with OS X Yosemite ver. 10.10.5 with one physical drive 256GB. This drive had 3 partitions: 1 - Mac, 2 - Mac Recovery, 3 - Win 7 64 bit. Due to low disk space on the Win 7 drive, I booted to OS X and shrunk the Macintosh HD partition by 25 GB. Then I created a 4th partition of 25 GB, which I planed to merge with the Win 7 partition. After doing this, there was no option to boot to Win 7 anymore. After restarting the MacBook, I had only two boot options instead of three: MAC and MAC recovery.

diskutil list:

Vladimirs-MBP:~ VK$ diskutil list  
/dev/disk0  
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *251.0 GB   disk0  
   1:                  Apple_HFS Macintosh HD            125.0 GB   disk0s1  
   2:                 Apple_Boot Recovery HD             650.0 MB   disk0s2  
   3:                  Apple_HFS Macintosh HD 2          24.9 GB    disk0s3  
   4:       Microsoft Basic Data Windows                 100.1 GB   disk0s4    

sudo fdisk /dev/disk0

sudo fdisk /dev/disk0
Disk: /dev/disk0    geometry: 30515/255/63 [490234752 sectors]  
Signature: 0xAA55  
         Starting       Ending  
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]  
------------------------------------------------------------------------  
 1: EE 1023 254  63 - 1023 254  63 [         1 -  490234751] <Unknown ID>  
 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  

In order to add partition 2, 3, 4 to the MBR, I need to know the "start" and "size" values, and in order to do that I need to use GPT. But when using GPT I get the following errors:

GPT

Vladimirs-MBP:~ VK$ sudo gpt -r show /dev/disk0  
gpt show: /dev/disk0: Suspicious MBR at sector 0  
gpt show: error: bogus map  
gpt show: unable to open device '/dev/disk0': Undefined error: 0  
  • Try sudo fdisk /dev/disk0. – David Anderson Jan 27 '18 at 3:36
  • These commands will dump the GPT. I will try to read the values directly from this output. sudo xxd -seek 512 -len 1024 -p /dev/disk0, sudo xxd -seek 251000176128 -len 512 -p /dev/disk0 and sudo xxd -seek 251000192512 -len 512 -p /dev/disk0 – David Anderson Jan 27 '18 at 15:29

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