Computer Froze, Now Raid over iSCSI (APFS Format) is no longer mountable. GPT/MBR not present

by Damian Cardona   Last Updated June 12, 2019 03:12 AM

I was exporting video in Premiere and the computer froze so I had to restart. Upon restarting, I noticed the raid drive I connect to over iSCSI was not showing up on my desktop. However, it appeared in Disk Utility. The Physical Disk and Container were opaque, but the volume (CC-SYN 1) was greyed out.

The Container in Disk Utility shows "1 Not Mounted, 63.74 TB" and "Free, 32.22 TB." Its physical stores is disk3s2. Device is disk4. The volume is disk4s1, shows a capacity of 95.96 TB, Zero KB available and -- for used. Says not mounted. When I try to mount is gives the error:

Could not mount “CC-SYN1”. ( error 49225.)

Running First Aid on the container and volume produces the following lines of errors in the details:

error: (oid 0x407) apfs_root: btn: invalid o_oid (0x403)
error: (oid 0x407) apfs_root: btn: invalid o_type (0xd)
error: (oid 0x407) apfs_root: btn: invalid o_subtype (0)
fsroot tree is invalid.
The volume /dev/rdisk4s1 could not be verified completely.

Running First Aid on the physical disk produces no errors.

diskutil apfs list shows the following information for the raid drive:

+-- Container disk4 6B51753E-274F-48BB-A0C2-89600A5B5DFF
    APFS Container Reference:     disk4
    Size (Capacity Ceiling):      95959023288320 B (96.0 TB)
    Capacity In Use By Volumes:   63742597726208 B (63.7 TB) (66.4% used)
    Capacity Not Allocated:       32216425562112 B (32.2 TB) (33.6% free)
    +-< Physical Store disk3s2 1E687745-0C0C-499E-BE56-6734C2909458
    |   -----------------------------------------------------------
    |   APFS Physical Store Disk:   disk3s2
    |   Size:                       95959023312896 B (96.0 TB)
    +-> Volume disk4s1 1BEFAA45-80CC-36F6-A360-C3B645F4687E
        APFS Volume Disk (Role):   disk4s1 (No specific role)
        Name:                      CC-SYN1 (Case-insensitive)
        Mount Point:               Not Mounted
        Capacity Consumed:         63740357574656 B (63.7 TB)
        FileVault:                 No


sudo gpt -r show disk4  
        start         size  index  contents
            0  23427495926         
sudo gpt -r show disk3s2
         start          size  index  contents
             0  187419967408         
sudo gpt -r show disk4s1
gpt show: unable to open device 'disk4s1': Permission denied

I have gdisk installed (from a prior raid storage size increase bug), and noticed the following problem when running the command - sudo gdisk /dev/disk4

GPT fdisk (gdisk) version 1.0.4

Partition table scan:
  MBR: not present
  BSD: not present
  APM: not present
  GPT: not present

The partition table prints:

Disk /dev/disk4: 23427495926 sectors, 87.3 TiB
Sector size (logical): 4096 bytes
Disk identifier (GUID): A8A7FBD2-665F-4081-BACC-6CB2D4FB8F18
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 5
First usable sector is 6, last usable sector is 23427495920
Partitions will be aligned on 256-sector boundaries
Total free space is 23427495915 sectors (87.3 TiB)


It seems that when the computer froze it basically destroyed the GPT/MBR and now the computer doesn't know how to mount it. I'm not 100% sure if gdisk has a workable solution to basically get the volume recognized again without losing data. Tried to read as much as I could but never had the confidence to pull the trigger on some of the commands that could result in potential data loss. Is there a way to fix this?

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