How to fix CoreStorage not mounting? Broken GPT, GUID, volume etc?

Question

I have an external hard drive with two partitions, each one formatted as "OS X Extended (Journaled, Encrypted)". The second partition mounts and asks for a password, but the first one does not. The hard drive is 1TB, the first partition is 895GB and the second partition is 104GB.

This is the output from diskutil list

/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk2
   1:                        EFI EFI                     209.7 MB   disk2s1
   2:          Apple_CoreStorage                         895.1 GB   disk2s2
   3:          Apple_CoreStorage Extra                   104.7 GB   disk2s3
   4:                 Apple_Boot Boot OS X               134.2 MB   disk2s4
/dev/disk3 (external, virtual):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                 Apple_HFSX Extra                  +104.4 GB   disk3
                                 Logical Volume on disk2s3
                                 888F03E6-B0A4-4E12-BA48-1DD1D1C3ED48
                                 Unlocked Encrypted

This is the output from sudo gpt -r show disk2

      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  1748305920      2  GPT part - 53746F72-6167-11AA-AA11-00306543ECAC
  1748715560        2008
  1748717568   204539864      3  GPT part - 53746F72-6167-11AA-AA11-00306543ECAC
  1953257432      262144      4  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
  1953519576           7
  1953519583          32         Sec GPT table
  1953519615           1         Sec GPT header

This is the output from sudo gpt -r show disk2s2. (The partition which won't mount).

   start        size  index  contents
       0  1748305920

This is the output from sudo gpt -r show disk2s3. (The partition which mounts).

  start       size  index  contents
      0  204539864

This is the output from sudo fsck_cs -y disk2s2. (The partition which won't mount).

   Executing fsck_cs (version 517.50.1)
** Checking volume
** disk2s2: Scan for Volume Headers
   Invalid Volume Header @ 0: unsupported format
   Invalid Volume Header @ 895132630528: invalid field value
** disk2s2 did not complete formatting as a CoreStorage volume

[Edit 1] Here is the output from diskutil cs list

CoreStorage logical volume groups (2 found)

+-- Logical Volume Group F99A19A9-A491-475F-8271-3601E6624322
|   =========================================================
|   Name:         MAINOS
|   Status:       Online
|   Size:         209200443392 B (209.2 GB)
|   Free Space:   4681728 B (4.7 MB)
|   |
|   +-< Physical Volume BA4F401C-1E9E-4236-9244-18DECF7A0E9C
|   |   ----------------------------------------------------
|   |   Index:    0
|   |   Disk:     disk0s2
|   |   Status:   Online
|   |   Size:     209200443392 B (209.2 GB)
|   |
|   +-> Logical Volume Family 41D930F7-7256-47C2-A660-B217DF788D79
|       ----------------------------------------------------------
|       Encryption Type:         AES-XTS
|       Encryption Status:       Unlocked
|       Conversion Status:       Complete
|       High Level Queries:      Fully Secure
|       |                        Passphrase Required
|       |                        Accepts New Users
|       |                        Has Visible Users
|       |                        Has Volume Key
|       |
|       +-> Logical Volume 7B8D4144-0957-4D2F-9B7B-6FF545C56555
|           ---------------------------------------------------
|           Disk:                  disk1
|           Status:                Online
|           Size (Total):          208843440128 B (208.8 GB)
|           Revertible:            Yes (unlock and decryption required)
|           LV Name:               MAINOS
|           Volume Name:           MAINOS
|           Content Hint:          Apple_HFS
|
+-- Logical Volume Group C909C3EC-B2C7-4E5A-B5EF-A9D18E3CA594
    =========================================================
    Name:         Extra
    Status:       Online
    Size:         104724410368 B (104.7 GB)
    Free Space:   1024000 B (1.0 MB)
    |
    +-< Physical Volume 628B789A-80D3-465E-A7CC-A5D45E57552D
    |   ----------------------------------------------------
    |   Index:    0
    |   Disk:     disk2s3
    |   Status:   Online
    |   Size:     104724410368 B (104.7 GB)
    |
    +-> Logical Volume Family BC19D010-6E0C-49F6-A6A7-92FF7DA5A972
        ----------------------------------------------------------
        Encryption Type:         AES-XTS
        Encryption Status:       Unlocked
        Conversion Status:       Complete
        High Level Queries:      Fully Secure
        |                        Passphrase Required
        |                        Accepts New Users
        |                        Has Visible Users
        |                        Has Volume Key
        |
        +-> Logical Volume 888F03E6-B0A4-4E12-BA48-1DD1D1C3ED48
            ---------------------------------------------------
            Disk:                  disk3
            Status:                Online
            Size (Total):          104371060736 B (104.4 GB)
            Revertible:            No
            LV Name:               Extra
            Volume Name:           Extra
            Content Hint:          Apple_HFSX

I believe the partition header is broken, but I'm unsure. It sounds similar to issues posted here and here. I don't know how to go about fixing this and getting that first partition to mount.

Welcome to Ask Different. You might need to edit in diskutil cs list to show what remnants of disk3s2 remain. Maybe someone is skilled enough to know, but that’s the first thing I would check to get more details what you expect to be from that CS volume. I’m assuming you are not wanting instructions on wiping and reinstalling - that’s trivial to answer. — bmike, Apr 05 '19 at 02:59
One of the questions you referenced mentions unlocking the core-storage volume. I assume then that some core storage volumes do not automount. Are you trying to manually mount the volume or do you want the volume to automount? In other words, I assume you tried diskutil cs unlockVolume 7B8D4144-0957-4D2F-9B7B-6FF545C56555 -passphrase passphrase, where you need to replace passphrase with the pass phrase assigned to the volume. — David Anderson, Apr 05 '19 at 07:37
@DavidAnderson, I am trying to manually mount the volume. Volume 7B8D4144-0957-4D2F-9B7B-6FF545C56555 is the volume of my OS hard drive that is running OS X and is already unlocked and attached as disk1. — AGG, Apr 05 '19 at 15:51
Did you ever resolve this? I have a client with the same problem..... — Zonker.in.Geneva, Feb 18 '20 at 12:17

score 1 · Answer 1 · answered Apr 05 '19 at 19:53

Your disk 2 doesn't even seem to have a name. It could be something simple - like the name accidentally deleted in Finder - or a serious inability of the OS to read the partition.

As you can't mount it without a name, I suppose it will also be difficult to change the name in Finder again, if that is the issue. Sometimes, a disk boots even if it has errors - did you try starting with the alt key? If it works, make sure to name the disk in Finder, preferably with the original name.

If that fails, first step is to save all data on the computer which you can still access.

If you have a backup of the data you can't access, the easiest solution is to delete the non-working partition and to restore it from the backup. Be aware that this involves a high risk of deleting the whole disk, deleting the wrong disk accidentally and so on. Not to mention that you permanently loose all data if your backup has issues. And you might get an unstable file system if there are still underlying issues.

If you have important data and no backups, you might want to consider professional data recovery. That costs some money, but the risk of accidentally loosing all through a wrong diskutil command or such is much lower.

If the data is wanted but not important enough to spend so much money on it, the next step is a disk repair app. You install it on a system on another disk (not just another partition) and let it do its magic. With a little bit of luck, all is at least fine enough for making a backup of the data before starting anew.

If there is any hardware issue at the root of your problem or coincidentally with your disk, anything you do, even if you make no mistakes, can end your disk (not just your partition).

If the disk repair app doesn't work or you don't want to spend the money, you may try a few terminal commands for renaming the partition. I'm not sure whether renaming works in terminal or whether this deletes the partition. And I'm not sure whether diskutil or diskutil cs commands are needed for that - try either, and preferably with the original name, if you remember it. A restart and it might or might not work.

I assume you already tried all repair options in Disk Utility and with the diskutil command. If renaming works but doesn't resolve the issue, try them again.

I don't see any more options right now.

Hi, I tried to rename the partition using diskutil. but It says I can't rename it if I can't mount it. I'm willing to try different diskutil commands on this drive as it is one of my backup drives and I would only lose some files. — AGG, Apr 05 '19 at 21:27

How to fix CoreStorage not mounting? Broken GPT, GUID, volume etc?

1 Answers1