How to change the GPT partition type of an EFI partition

bootefipartition

I have a perplexing problem with the EFI partition on my boot SSD. The GPT partition type is "Microsoft Basic Data". On all other drives in my system, including my Carbon Copy Cloner clone of my boot drive, the partition type is "EFI" (see below):

$ diskutil list
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *512.1 GB   disk0
   1:       Microsoft Basic Data EFI                     209.7 MB   disk0s1
   2:                  Apple_HFS Tims Boot SSD           498.7 GB   disk0s2
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *960.2 GB   disk1
   1:                        EFI EFI                     209.7 MB   disk1s1
   2:                  Apple_HFS Users                   959.9 GB   disk1s2

...

/dev/disk4
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *512.1 GB   disk4
   1:                        EFI EFI                     209.7 MB   disk4s1
   2:                  Apple_HFS Tims Boot SSD Clone     511.8 GB   disk4s2

My system boots just fine, but it appears to be loading the bootloader (Clover in this case) from the /Users drive (disk1) instead of from the boot SSD (disk0), and I think the incorrect GPT partition type is to blame.

I tried to update the partition type using the "asr adjust" command as outlined at https://unix.stackexchange.com/questions/58705/mac-os-x-partition-type-problem, but it doesn't work and gives me a very unhelpful error message:

$ sudo asr adjust --target /dev/disk0s1 --settype EFI
asr: Volume adjustment failed: Unknown error: -123

I have found information about other possible ways to set the GPT partition type through Google searches, but all the other methods seem risky, with warnings about erasing the partition in question, etc.

Does anyone know how I can fix this?

Best Answer

I recreated your problem using a 4 GB flash drive. Below is the output from the command diskutil list /dev/disk1.

/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *4.0 GB     disk1
   1:       Microsoft Basic Data EFI                     209.7 MB   disk1s1
   2:                  Apple_HFS Tims Boot SSD           3.7 GB     disk1s2

Below is the output from the command sudo gpt -r show /dev/disk1

    start     size  index  contents
        0        1         PMBR
        1        1         Pri GPT header
        2       32         Pri GPT table
       34        6         
       40   409600      1  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
   409640  7220264      2  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
  7629904   262150         
  7892054       32         Sec GPT table
  7892086        1         Sec GPT header

The problem is the partition type GUID for the EFI partition is EBD0A0A2-B9E5-4433-87C0-68B6B72699C7 and it should be C12A7328-F81F-11D2-BA4B-00A0C93EC93B.

To correct this, I entered the following commands. In your case, you would substitute disk0 for disk1. You should enter these commands from the bootable USB backup clone of your boot drive.

diskutil unmountdisk /dev/disk1
sudo gpt remove -i 1 /dev/disk1
diskutil unmountdisk /dev/disk1
sudo gpt add -i 1 -b 40 -s 409600 -t C12A7328-F81F-11D2-BA4B-00A0C93EC93B /dev/disk1

Before entering type above commands, make sure your start and size entries are 40 and 409600, respectively. If not, make the appropriate corrections to the -b and -s options.

Related Solutions

MacOS – Can’t modify partitions

Thanks @Tetsujin. The listing looked a little screwy so I was a little hesitant to go mucking around with the command-line diskutil. But I ended up doing a

diskutil corestorage list

and then

diskutil corestorage delete [UUID of 50GB Logical Volume Group]

GUI Disk Utility correctly saw the 50 GB of empty space as part of the other Logical Volume Group and I was able to delete it and merge it back in fine.

I think I messed up the Fusion Drive on the 1TB iMac (with BootCamp)

Theoretically everything is fine with your Fusion Drive. Fusion Drives look like this. Disk0 is your SSD with 121 GB and disk1 is your HDD with ~1 TB (~1.121 TB summed up).

The larger parts of your SSD (disk0s2) and your HDD (disk1s2) are pooled to a CoreStorage LVG (Fusion Drive: disk3) with a size of 967.8 GB. The rest is reserved for EFIs, a Recovery HD (alltogether ~1.3 GB) and your old Windows partition - now probably free space (~152 GB).

The logical volume 'Macintosh HD' (967.8 GB) spans disk0s2 and disk1s2. This is the first 'Macintosh HD' in picture 1. The volume 'Macintosh HD' - it's the one visible on the desktop - should ideally also have about 967.8 GB. This is the second 'Macintosh HD' in picture 1.
In fact it has only 852.67 GB (see picture 3).

In the second picture the logical volume 'Macintosh HD' is the first listed in black, the volume 'Macintosh HD' is the second listed in black, the other two 'Macintosh HD's listed in grey are the parts of your SSD and HDD dedicated to the logical volume 'Macintosh HD'.

In my opinion something went wrong after deleting various partitions with the Bootcamp Assistant/Disk Utility or in Windows.

Preparation:

Detach any external drive (especially your external Time Machine backup drive)
Restart to Internet Recovery Mode by pressing alt cmd R at startup.
The prerequisites are the latest firmware update installed, either ethernet or WLAN (WPA/WPA2) and a router with DHCP activated.
On a 50 Mbps-line it takes about 4 min (presenting a small animated globe) to boot into a recovery netboot image which usually is loaded from an apple/akamai server.

I recommend ethernet because it's more reliable. If you are restricted to WIFI and the boot process fails, just restart your Mac until you succeed booting.

Alternatively you may start from a bootable installer thumb drive (preferably Mavericks or Yosemite) or a thumb drive containing a full system (preferably Mavericks or Yosemite).

Now you may either repair CoreStorage or rebuild your Fusion Drive:

'Repair CoreStorage' (not recommended):

First i would try to check the volume 'Macintosh HD' with Disk Utility. If the volume is corrupted consider a reinstall of Mac OS X.
If the volume is ok quit Disk Utility
Open Terminal and enter diskutil unmountDisk /dev/LVIdentifier and both diskutil unmountDisk /dev/DiskContainingApple_CoreStorageIdentifier
In your case: first diskutil unmountDisk /dev/disk3 then diskutil unmountDisk /dev/disk0 and diskutil unmountDisk /dev/disk1
remove the EFI NO NAME partition with gpt remove -i IndexNumberOfEFINoName DiskIdentifier:
gpt remove -i 4 disk1
Remount the CoreStorage disks and then the Logical Volume:
In your case: first diskutil mountDisk /dev/disk0 and diskutil mountDisk /dev/disk1 and then diskutil mount /dev/disk3.

enter gpt -r -vvv show /dev/diskIdentfierOfApple_CoreStorage to get infos of your HDD CoreStorage disk.
In your case: gpt -r -vvv show /dev/disk1
It should look like this:

-bash-3.2# gpt -r -vvv show /dev/disk1
gpt show: /dev/disk1: mediasize=1000204886016; sectorsize=512;         blocks=1953525168
gpt show: /dev/disk1: PMBR at sector 0
gpt show: /dev/disk1: Pri GPT at sector 1
gpt show: /dev/disk1: GPT partition: type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B, start=40, size=409600
gpt show: /dev/disk1: GPT partition: type=53746F72-6167-11AA-AA11-00306543ECAC, start=409640, size=1671210848
gpt show: /dev/disk1: GPT partition: type=426F6F74-0000-11AA-AA11-00306543ECAC, start=1671620488, size=1269760
gpt show: /dev/disk1: Sec GPT at sector 1953525167                               
     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    1671210848      2 GPT part - 53746F72-6167-11AA-AA11-00306543ECAC
1671620488       1269760      3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
1672890248     280634887
1953525135            32        Sec GPT table
1953525167             1        Sec GPT header

The free space on your HDD has 280634887 blocks. Please calculate the biggest block number dividable through 8. That's 280634880 blocks (á 512 bytes) which equals 143685058560 B or ~143.7 GB. Add the size of your HDD CoreStorage Physical Volume (852666400768 B) The result is 143685058560 B + 852666400768 B = 996351459328 B
Resize your HDD CoreStorage physical volume with diskutil cs resizeDisk HDDPVUUID newsize
In your case: diskutil cs resizeDisk 93892BE8-2B7F-4ABD-A4C3-984495DCD98D 996351459328b
Calculate the maximal size of your CoreStorage Logical Volume in diskutil cs list: (size disk0s2) + (size disk1s2) In your case that's 120988852224 B + 996351459328 B = 1117340311552 B. That should be the size of your refreshed Logical Volume Group.
Resize your Logical Volume with diskutil cs resizeVolume LVUUID LVGSize-128 MB In your case that's diskutil cs resizeVolume D237FFDC-7DA4-41D7-AC13-4CC7E5E8C0A0 1117212311552b. If you get an error (There is not enough free space...) choose a smaller size like 1117148311552b.
Quit Terminal and open Disk Utility.
Check your expanded CoreStorage Volume for errors.
Quit Disk Utility, choose your CS volume as startup disk and restart your Mac

'Rebuild Fusion Drive' (recommended if you have a Time Machine backup)

Booted to Internet Recovery Mode open Utilities → Terminal in the menubar and enter:
diskutil cs list to get the CoreStorage listing.
Copy the Logical Volume UUID, it's the fifth listed.
Now delete the Logical Volume with diskutil cs deleteVolume LVUUID.
In your case: diskutil cs deleteVolume D237FFDC-7DA4-41D7-AC13-4CC7E5E8C0A0.
Copy the Logical Volume Group UUID, it's the first listed in the listing of diskutil cs list.
Then delete the Logical Volume Group with diskutil cs delete LVGUUID.
In your case: diskutil cs delete 1EFE58BC-3613-44C4-86EE-D816F3B66E3E
Enter exit and quit 'Terminal'
Open 'Disk Utility'. Enter 'Ignore' if you are asked to fix the drives.
Choose your SSD and partition it: 1 Partition Mac OS X Extended (Journaled), hit the Options button and choose GUID Partiton table and hit OK and Apply.
Please check that the size is ~121 GB

Example:
Choose your HDD and partition it: 1 Partition Mac OS X Extended (Journaled), hit the Options button and choose GUID Partiton table and hit OK and Apply.
Please check that the size is ~1 TB

Example:
Quit Disk Utility and open Terminal
Enter diskutil list

Example (your disk identifiers and sizes are different of course: Your volume SSD probably has the Identifier disk0s2 and the size 121 GB and your volume HDD probably has the Identifier disk1s2 and the size 1.0 TB):
Enter diskutil cs create "Name" IdentifierSSD IdentifierHDD
In your case probably diskutil cs create "Macintosh HD" disk0s2 disk1s2.

Copy the resulting LVGUUID

Example:
Enter diskutil cs CreateVolume LVGUUID jhfs+ "Macintosh HD" 100%.

Example:
Enter diskutil cs list
Check the size of your Logical Volume. It should have the size ~1.121 TB

Example:
Quit Terminal
Open 'Disk Utility' and check your newly created volume for errors
Quit 'Disk Utility'
Attach your external Time Machine backup drive or check this answer if you use NAS or another network share.
Open 'Restore from Time Machine Backup'
Choose the appropriate Time Machine backup and restore your system
Reboot to your restored system.
Unmount and detach your Time Machine backup drive
Open 'Terminal' and enter 'diskutil list'
Check if your 'Recovery HD' is listed.
If your 'Recovery HD' is missing, usually reinstalling your current system with the latest available system installer (e.g. 'Install OS X Mavericks (10.9.5)' if Mavericks is currently installed) will recreate it without loosing any data. AFAIK Recovery Partition Creator 3.8 will NOT create a Recovery HD on CoreStorage volumes.
After reinstalling the system with the latest available system installer open App Store and install the latest security fixes.

Best Answer

Related Solutions

MacOS – Can’t modify partitions

I think I messed up the Fusion Drive on the 1TB iMac (with BootCamp)

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