A few years ago I created a second boot partition on a MacBook, called "BootOS". I would like to delete this partition and merge the space back into the remaining partition.

I have found a question/answer that describes how to do this on El Capitan, but the output from diskutils list on Catalina looks sufficiently different for me to ask again.

Can anyone suggest suggest how I should go about this?

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_APFS Container disk2         937.0 GB   disk0s2
   3:          Apple_CoreStorage BootOS                  62.7 GB    disk0s3
   4:                 Apple_Boot Recovery HD             650.0 MB   disk0s4

/dev/disk1 (internal, virtual):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS BootOS                 +62.3 GB    disk1
                                 Logical Volume on disk0s3

/dev/disk2 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +937.0 GB   disk2
                                 Physical Store disk0s2
   1:                APFS Volume Macintosh HD - Data     850.8 GB   disk2s1
   2:                APFS Volume Preboot                 85.1 MB    disk2s2
   3:                APFS Volume Recovery                526.6 MB   disk2s3
   4:                APFS Volume VM                      1.1 GB     disk2s4
   5:                APFS Volume Macintosh HD            11.0 GB    disk2s5

diskutil cs list :

CoreStorage logical volume groups (1 found)
+-- Logical Volume Group 1C402269-ED55-46B6-B2B3-2C83C455625C
    Name:         BootOS
    Status:       Online
    Size:         62708625408 B (62.7 GB)
    Free Space:   18984960 B (19.0 MB)
    +-< Physical Volume 8A71BD1E-3901-4573-8ABA-B635F6957E9B
    |   ----------------------------------------------------
    |   Index:    0
    |   Disk:     disk0s3
    |   Status:   Online
    |   Size:     62708625408 B (62.7 GB)
    +-> Logical Volume Family CD18710F-BC90-4354-843B-C8B35B34274A
        Encryption Type:         None
        +-> Logical Volume 98445A01-48FA-4E17-8CDE-61C46B885B90
            Disk:                  disk1
            Status:                Online
            Size (Total):          62337318912 B (62.3 GB)
            Revertible:            Yes (no decryption required)
            LV Name:               BootOS
            Volume Name:           BootOS
            Content Hint:          Apple_HFS
  • I'll take a stab at an answer - I don't have a test system to run thought - you might not need the cs delete once you've ejected disk1 - but the rest are pretty straightforward
    – bmike
    Mar 7, 2020 at 16:59

2 Answers 2


Disk Utility.app in the /Applications/Utilities/ folder would be my recommendation. That's generally the easiest/safest way to make changes to partitions.

  • I tried diskutil first, but the BootOS volume doesn’t seem to be removable. Perhaps I should erase it first.
    – Seb Rose
    Mar 7, 2020 at 21:53

what about:

diskutil ejectDisk disk1
diskutil cs delete disk0s3

That cleans the space that was reserved and the next says grow to fit (since it doesn't make sense to size an exiting container to 0 - that is a shortcut to grow as far as it can)

diskutil apfs resizeContainer disk0s2 0

Of course if you or I am wrong, you need a backup of everything so I hope you have that before starting.

  • I do have a backup. I’d prefer not to have to use it ;)
    – Seb Rose
    Mar 7, 2020 at 21:55
  • I think you’ll be fine if you copy and paste the disk0s2 from your listing and double check you didn’t miss a column / row
    – bmike
    Mar 7, 2020 at 21:57

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .