MacOS – How to fix broken GPT, GUID and unmountable and without type volumes

efiguidmacbook promacosmount

I have Macbook pro with mavericks and 512GB SSD i accidentally deleted a partition and suddenly my mac could not boot any more and after i tried to do something with disk utility this is gpt -r show disk0 command output:

    start        size  index  contents
        0           1          PMBR
        1           1          Pri GPT header
        2          32          Pri GPT table
       34      409606          
   409640   823778456       1  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
824188096     1269536       2  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
825457632    24695840     
850153472   126951424       3  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B    
977104896         131
977105027          32          Sec GPT table
977105059           1          Sec GPT header

So i followed the soultion on this link and do this command sudo gpt remove -i 1 disk0 then i countinued with this command:

sudo gpt add -b 40 -i 1 -s 409600 -t C12A7328-F81F-11D2-BA4B-00A0C93EC93B disk0

and the gpt -r show disk0 command output become like this:

    start        size  index  contents
        0           1          PMBR
        1           1          Pri GPT header
        2          32          Pri GPT table
       34           6
       40      409600       1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
   409640   823778456      
824188096     1269536       2  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
825457632    24695840     
850153472   126951424       3  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B    
977104896         131
977105027          32          Sec GPT table
977105059           1          Sec GPT header

and i realized i deleted Macintosh HD volume index so i kept manipulating the table until the gpt -r show disk0 command output becomes like this

    start       size  index   contents
        0          1          PMBR
        1          1          Pri GPT header
        2         32          Pri GPT table
       34          6         
       40     409600       1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
   409640  823778456       2  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
824188096    1269536       3  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC     
825457632  151647395
977105027          32          Sec GPT table
977105059           1          Sec GPT header

but still have the same problem here i did this command dd if=/dev/disk0s2 of=/Volumes/APP/Mac.iso to backup this volume in external HDD and i tried to open this iso with peazip in windows vista but i can not see nothing inside did i backup my data with the command i mentioned? and how can i get the data out of Mac.iso file?

then i tried this command newfs_msdos -v EFI /dev/disk0s1 and suddenly the SDD turns to MBR and no volumes there, so i used command to create gpt table and this was successfully done and i make the changes to go to the original table also i play with disk utility and this is my current situation:

diskutil list disk0 command output:

   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.3 GB   disk0
   1:                  Apple_HFS                         421.8 GB   disk0s1
   2:                 Apple_Boot                         650.0 MB   disk0s2
   3:                  Apple_HFS Untitled 2              12.5 GB    disk0s3
   4:                        EFI                         65.0 GB    disk0s4

and this is gpt -r show disk0 output:

    start        size  index  contents
        0           1          PMBR
        1           1          Pri GPT header
        2          32          Pri GPT table
       34      409606          
   409640   823778456       1  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
824188096     1269536       2  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
825457632    24433696       3  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
849891328      262144
850153472   126951424       4  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B    
977104896         131
977105027          32          Sec GPT table
977105059           1          Sec GPT header

Now, the Macintosh HD volume shows in disk utility as disk0s1 and it is not mountable and also i tried linux live cd and gparted (disk management application) could not recognize volumes types accept for Untitled 2 volume that i created with disk utility not by using commands.

Please help me in fixing my problem to enter OS X and my data or in mounting Macintosh HD volume and put volumes types without format because i want to backup my data before re-install OS X.

Thank you.

Best Answer

If you have a spare linux box you can try to use SystemRescueCD to mount and possibly recover the data on your Mac (hfs+) partitions.

SystemRescueCD

The SystemRescueCD contains TestDisk which I have used to recover data from Linux, Windows as well as Mac file systems:

TestDisk

I think there is also a TestDisk Mac app you can install and run from a Mac OS computer, so as long as you can mount your bad drive you can use TaskDisk to try to receover the data. But I have not tried this so you might have to test it out first on a dummy drive before working on your real drive.

Related Solutions

MacOS – How to fix the GPT

A PRAM / NVRAM reset (⌘-⌥-P-R on startup) fixed the delay. The Disk Utility error report remains. Started again from my old drive, the error is reported there as well... probably it was there before the migration.

EFI Partition – Fixing The Broken EFI in macOS

You can recreate the EFI System Partition (ESP) using the command-line gpt tool. It should start at sector 40, and it should be 409600 sectors (exactly 200MiB) long. The GPT entry's type should be C12A7328-F81F-11D2-BA4B-00A0C93EC93B, and if you have a hybrid MBR, the type there should be EE. The format is actually a subset of FAT, not HFS+. You can read the GPT using the command sudo gpt -r show disk0 in a Terminal window, this produces output that looks something like this:

      start       size  index  contents
          0          1         PMBR
          1          1         Pri GPT header
          2         32         Pri GPT table
         34          6         
         40     409600      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
     409640  447801712      2  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
  448211352    1269536      3  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
  449480888   40753831         
  490234719         32         Sec GPT table
  490234751          1         Sec GPT header

You can see the correct EFI partition at index 1. If that line doesn't match exactly, the easiest way is to delete the partition in its place and recreate it.

Make sure you know what you're doing before proceeding from here - you may lose data if you mess up.

You can't edit the partition table using gpt while partitions on the drive are mounted, so you'll need to boot from another drive (e.g. a USB stick with the OSX installer) or run the mac in target disk mode and do the partitioning from another mac. You may need to unmount any automatically mounted volumes using diskutil unmountDisk disk0 before proceeding, and in between commands.

To delete your "bad" EFI partition, run this command:

sudo gpt remove -i 1 disk0

Make sure disk0 is really the disk you want to change - the numbers can change between reboots. Also, this will only work if you already have a non-ESP partition in the place of the ESP - if not, deleting partition 1 could be disastrous! In this case, you'll need to move the indices along, as I think the ESP must have index 1. By the sound of it, this won't be necessary in your case.

Once deleted, re-add the partition with the correct layout and type:

sudo gpt add -b 40 -i 1 -s 409600 -t C12A7328-F81F-11D2-BA4B-00A0C93EC93B disk0

This should sort out the partition itself, but as you've created an HFS partition in its place, you need to fix its format as well.

The format of the EFI System Partition is documented by Apple here. As you can see, they recommend you clone an existing ESP rather than recreating the file system with newfs_msdos. If you have an external drive with a GPT partition table (OSX install stick should have it), you can clone that.

Make sure you have your disk and partition numbers the right way around or you may overwrite data:

If disk1 is your external drive, and it contains an ESP as the first partition (disk1s1) and disk0 is the drive whose ESP (disk0s1) you want to fix, run this command:

sudo dd if=/dev/disk1s1 of=/dev/disk0s1

This will copy every single block of disk1's ESP and overwrite the corresponding block in disk0's ESP with it.

Alternatively, take a gamble with newfs_msdos.

Best Answer

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MacOS – How to fix the GPT

EFI Partition – Fixing The Broken EFI in macOS

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