IMac – Hard Drive not showing up in Disk Utility

disk-utilityhard driveimac

So I arrived home from school today and wanted to use my iMac, but somehow it wouldn't react. I pressed the power button until it shut down (or crashed…) and rebooted it. After rebooting everything seemed normal, but there was this error, that the keychain login couldn't be accessed. After googling and seeing, that the login keychain was missing in "Keychain Access", I decided to restore my Time Machine Backup from the evening before. After TM failed the first attempt (Shut down at 20%) I tried again, but somehow everything got fucked up.

I don't remember 100% exactly how everything happened, but the end result now is, that I do not see the HDD of my Fusion Drive CoreStorage. The SSD is visible in Disk Utility, but not the HDD. It also is not shown in "diskutil list" and not shown in Parted Magic. I also tried booting while holding the "D" key to enter Apple Hardware Test, but the result was, that everything is okay…

I'm really desperate right now, because I didn't had a very good mood when I came home and now the day is totally trash. I really appreciate every bit of help or information, that could help me..

If you have questions, don't hesitate to ask.

EDIT:
– I tried to reset the SMC (unplug the iMac from power for 15 seconds) and it changed nothing.

The terminal outputs of diskutil list,diskutil cs list, gpt -r show disk0/disk1: 

-bash-3.2# diskutil list
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *121.3 GB   disk0
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     Apple_partition_scheme                        *1.2 GB     disk1
   1:        Apple_partition_map                         30.7 KB    disk1s1
   2:                  Apple_HFS Mac OS X Base System    1.2 GB     disk1s2
/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               *524.3 KB   disk2
   ....

-bash-3.2# diskutil cs list
No CoreStorage logical volume groups found
-bash-3.2# gpt -r show disk0
      start       size  index  contents
          0          1         PMBR
          1          1         Pri GPT header
          2         32         Pri GPT table
         34  236978109        
  236978143         32         Sec GPT table
  236978175          1         Sec GPT header

-bash-3.2# gpt -r show disk1
    start     size  index  contents
        0  2330500

Best Answer

The SSD is disk0, the internal HDD (which should be disk1 if a Fusion disk is attached) is missing. Instead your recovery volume (loaded from Apple) is disk1.

Your internal HDD probably either died or the SATA cable is loose/broken. You have to replace the HDD and/or the cable.

The SSD seems to be functional but misses any partition. It already contains a GUID partition table though.

If the size of the backup data is smaller than ~118 GB (which is unlikely) you should be able to restore it after adding a partition. Otherwise you have to replace the HDD part of the Fusion disk and restore the backup later.

A temporary work-around is to restore OS X after adding a partition in Internet Recovery Mode, updating to your current OS X and then use the Migration Assistant to only import the most important data.

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