I have 399.9GB OSX partition, but the HDD is actually 1TB.

If I click on the partition tool, I then have 999GB displayed (with are not in the partition)

if I try to resize the volume I'm getting a error.

I first thought this was because the disk was encrypted, so I removed the encryption, but same issue, rebooted from internet recovery wasn't even able to erase the whole disk.

Current volume



$ sudo gpt -r show disk0
gpt show: unable to open device 'disk0': Operation not permitted

$ diskutil cs list
CoreStorage logical volume groups (1 found)
+-- Logical Volume Group 061EBFDF-338D-4126-9D5B-5429081998BC
    Name:         Macintosh HD
    Status:       Online
    Size:         400269959168 B (400.3 GB)
    Free Space:   15912960 B (15.9 MB)
    +-< Physical Volume 836846BB-F307-4BD1-B8A6-B4653DD9DA33
    |   ----------------------------------------------------
    |   Index:    0
    |   Disk:     disk0s2
    |   Status:   Online
    |   Size:     400269959168 B (400.3 GB)
    +-> Logical Volume Family F92C105A-7731-4726-A953-D98C4AEEC998
        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 0FBB6ED9-C176-480D-A7B4-39C655262C2C
            Disk:                  disk1
            Status:                Online
            Size (Total):          399901720576 B (399.9 GB)
            Revertible:            No
            Revert Status:         Reboot required
            LV Name:               Macintosh HD
            Volume Name:           Macintosh HD
            Content Hint:          Apple_HFSX

$ diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:          Apple_CoreStorage Macintosh HD            400.3 GB   disk0s2
   3:                 Apple_Boot Recovery HD             598.9 GB   disk0s3
   4:       Apple_KernelCoreDump                         789.6 MB   disk0s4

/dev/disk1 (internal, virtual):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS Macintosh HD           +399.9 GB   disk1
                                 Logical Volume on disk0s2
                                 Unlocked Encrypted

diskutil ap list
No APFS Containers found
  • Thank you for your reply, I've just updated the post with the result
    – Kevin
    Commented Nov 20, 2017 at 14:40
  • updated, the 399GB is my current partition with my OS, but not sure what the another and why are not displayed on disk utility, and 500GB+ for a recovery it's a lot no?
    – Kevin
    Commented Nov 20, 2017 at 14:49
  • Sorry, 10.13.1 (17B48), I had a partition in High Sierra before but had the same issue, couldn't even erase it, managed to do it from booting to a colleague iMac (his mac in Target mode), boot from his recovery and erased mine (at least I thought I did) then I install Siera and updated to High Sierra
    – Kevin
    Commented Nov 20, 2017 at 14:55

1 Answer 1


That's Mixed Hostile Partition Arts. Your partition layout is non-standard:

  • Apple_KernelCoreDump (789.6 MB disk0s4): probably a leftover of a High Sierra Beta install
  • Recovery HD (598.9 GB disk0s3): ~920 times too large. The standard size in non-APFS systems is 650.0 MB.

I recommend to backup your main volume (Macintosh HD) with Time Machine, completely erase the whole disk booted to Internet Recovery Mode and reinstall macOS High Sierra and migrate the backup (or restore the backup after erasing the disk).

A second approach is to reboot (Revert Status: Reboot required!), decrypt the drive if necessary and revert to non-CoreStorage. Then verify disk and main volume:

diskutil verifyDisk disk0
diskutil verifyVolume disk0s2

and repair if required.

Then merge disk0s2, disk0s3 and disk0s4:

diskutil mergePartitions HFS+ "Macintosh HD" disk0s2 disk0s4

This will merge disk0s2 (your old Macintosh HD), disk0s3 and disk0s4 into disk0s2 while preserving the content of disk0s2. I never had a problem merging slices like this but it's always beneficial to have a working (Time Machine) backup of disk0s2 (your Macintosh HD) before merging partitions.

If this step fails to merge the partitions (e.g disk0s4 is "in use"), boot to Internet Recovery Mode and try it again.

Verify disk and main volume again:

diskutil verifyDisk disk0
diskutil verifyVolume disk0s2

Then download and reinstall the latest macOS High Sierra to recreate the recovery partition. I don't think that Recovery Partition 4.0.4 is compatible with High Sierra already.

Finally enable FileVault again.

  • Many thanks for your answer, I will try to do this soon.
    – Kevin
    Commented Nov 20, 2017 at 16:05

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