MacOS – Fusion drive unavailable after HD erase

core-storagemacos

I wanted to erase the 3 TB Fusion HD on my iMac in order to install a clean system and start from scratch. The erase went fine except right at the end when it said something about core storage… (which I failed to capture, sorry)… and now the machine behaves as though the drive only sort of half exists.

There is no 'sub-disk' when I look with Disk Utility – i.e., there is no indented drive listed below "Macintosh HD"
The "Erase" tab is absent in Disk Utility
All partition options are greyed out in Disk Utility
I can boot in Recovery Mode, but I can't reinstall OS X because there is no drive available – it asks me to select a disk, but no disks are listed
diskutil sees the drive fine (screenshots below)

In case it's not clear from the images, distil cs list shows:

Logical Volume Group C970ADA-0D05-42AA-9E9C-403ED0E5335
Name: Macintosh HD
Status: Online
(3.1Tb)

    Physical Volume 7DAE3935-D0AD-42AE-AE2A-F6001F09187
    Index: 0
    Disk: disk0s2
    (120Gb)

    Physical Volume BA37C009-F93C-4EAF-9EF3-9C19772BD91C
    Index: 1
    Disk: disk1s2
    (3Tb)

diskutil list shows:

Best Answer

You probably deleted your Logical Volume and the superior Logical Volume Family.

To create a new one boot to Recovery Mode, open Terminal and simply enter:

diskutil cs list #to get the lvgUUID (UUID of the Logical Volume Group)
diskutil cs createVolume lvgUUID type name size

or in your case:

diskutil cs createVolume C970ADA-0D05-42AA-9E9C-403ED0E5335 jhfs+ "Macintosh HD" 100%

Related Solutions

MacOS – Unable to reformat/repartition CoreStorage logical volume (Fusion drive)

I was able to delete a mess I made trying to delete my Raid 10 in diskutil (which ended up looking similar to above) using the commands below in Terminal.app. May or may not work with fusion but it's easier than booting up again.

Get rid of the volume - copy paste the logical volume name where it says "Logical Volume Name", without the quotes:

diskutil cs deleteVolume "*Logical Volume Name*"

Free the disk - copy paste the volume name where it says "Physical Volume Name", without the quotes:

diskutil cs removeDisk "*Physical Volume name*"

Repeat these steps as needed.

Mac – Why does Disk Utility show one “Macintosh HD” as a logical drive and another that says core storage physical volume

[Edited to reflect screen shots]

Technically that is 1 Hard Drive and 4 partitions (see how they are all indented from the drive they are in).

It looks like someone enabled showing all volume types in your Disk utility so it's showing you things not normally shown in the GUI.

OS X has something like LVM so you are seeing the Logical Volume (LV) and the CoreStorage (PV) both shown as partitions in Disk Utility. LVM provides many advantages over using a regular partition none of which are assessable in the OS X GUI, but you can read more about it on that link if you are interested. In Linux disks, logical volums, etc are labeled different from eachother but on OS X a disk can be /dev/disk0 and a LV can be /dev/disk1 which can be confusing because they are different in many ways.

Normaly you can only see the partitions that don't directly contain data by opening Terminal.app running diskutil list.

So you may want to disable that setting to put the GUI back to it's simple defaults.

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