Unable to create partition on free space using disk utility

disk-utility

Running 10.13.4 on a MBP with 750GB SSD.

The problem
i started with a single APFS container that spanned the whole 750GB of the internal SSD disk. Only half of it was in use so i decided to free the unused half and use it to create an additional APFS container (for reasons, please see below). I ran the diskutil resizecontainer command to free the space and that succeeded. I then ran disk utility guy and selected the whole disk and then partition. This shows the free space and the existing APFS container. I was hoping that when i click on the free space i would be able to partition it and go from there but the add functionality (+ sign) is greyed out as are the partition information details. Why is that? Is there a way to regain access to this free space and assign it to a new partition without zapping the whole disk and starting again? Pictures below.

Why I want to create extra APFS partitions.
I see lots of admonitions to only create one APFS container as APFS is designed to share space and volumes will grow and shrink and you don't have to worry, etc. But i also see that 'your startup disk is filling up' is quite a common occurrence after a while. Seems to me that the solution to that is to ring fence the space that your startup disk is sitting on so that the rest of the disk can fill up without any risk to the system. I have no control over the creation of the 'Macintosh HD' volume (or the other 3 volumes that are created at install) and it seems that once an APFS volume has been created there is no way to resize it.The best I can hope for is to resize the container of the startup disk and use the free space to create an additional APFS container which will then house the user data.

Thanks in advance.

diskutil apfs list before i started

diskutil list before i started

diskutil list after resizecontainer shrinkage

Disk Utility GUI showing free space and + button as well as Name, Format and Size fields greyed out

Best Answer

Both the Disk Utility application and diskutil command do not allow free space to be converted to a new partition. Instead, you are suppose to create new partitions by splitting an existing partition.

So first of all, enter the command given below to reclaim the free space to the existing APFS partition.

diskutil apfs resizecontainer disk0s2 0

Open the Disk Utility application and highlight the container disk1, then click on the Partition button. You should get an image similar to what is shown below.

Next, click on the Partition button in the popup window. You should get an image similar to what is shown below.

Click on the +button, then enter a name. I chose Macintosh HD 2. Make sure the format is APFS and the size is 350 GB. The result should be an image similar to what is shown below.

Next, click on the Apply button. You should get an image similar to what is shown below.

Next, click on the Partition button in the popup window. The result should be an image similar to what is shown below.

Note: The Disk Utility application may show incorrect results. You may need to quit and reopen the Disk Utility application to see the correct results.

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MacOS – Clear free space in Disk Utility

Preparation:

Backup 'Macintosh HD'
Start another computer or smartphone and access this page here to follow the instructions.
Detach any external drive (especially an external Time Machine backup drive)
Restart to Internet Recovery Mode by pressing alt cmd R at startup.
The prerequisites are the latest firmware update installed, either ethernet or WLAN (WPA/WPA2) and a router with DHCP activated.
On a 50 Mbps-line it takes about 4 min (presenting a small animated globe) to boot into a recovery netboot image which usually is loaded from an apple/akamai server.

I recommend ethernet because it's more reliable. If you are restricted to WIFI and the boot process fails, just restart your Mac until you succeed booting.

Alternatively you may start from a bootable installer thumb drive (Mavericks or Yosemite) or a thumb drive containing a full system (Mavericks or Yosemite).

Revert CoreStorage Volume

Check the volume 'Macintosh HD' with Disk Utility and repair it if necessary. If the volume is corrupted beyond any repair consider a reinstall of Mac OS X.
If the volume is OK quit Disk Utility

Open Terminal from the menubar (Utilities/Terminal) and enter diskutil cs list. The output will be this:

CoreStorage logical volume groups (1 found)
|
+-- Logical Volume Group 25AF6969-0B3A-4C2C-BE38-29864C233F66
    =========================================================
    Name:         Macintosh HD
    Status:       Online
    Size:         801345126400 B (801.3 GB)
    Free Space:   18907136 B (18.9 MB)
    |
    +-< Physical Volume 21095CB1-4D76-44F5-B438-0B84A06AB0E8
    |   ----------------------------------------------------
    |   Index:    0
    |   Disk:     disk0s2
    |   Status:   Online
    |   Size:     801345126400 B (801.3 GB)
    |
    +-> Logical Volume Family 2DDF1B89-E73A-45E7-96CD-5FA1DC9CA275
        ----------------------------------------------------------
        Encryption Status:       Unlocked
        Encryption Type:         None
        Conversion Status:       NoConversion
        Conversion Direction:    -none-
        Has Encrypted Extents:   No
        Fully Secure:            No
        Passphrase Required:     No
        |
        +-> Logical Volume 54E92188-CDD5-44AE-9D58-EF6A5B69D707
            ---------------------------------------------------
            Disk:                  disk1
            Status:                Online
            Size (Total):          800973897728 B (801.0 GB)
            Conversion Progress:   -none-
            Revertible:            Yes (no decryption required)
            LV Name:               Macintosh HD
            Volume Name:           Macintosh HD
            Content Hint:          Apple_HFS

Copy the UUID of the Logical Volume (lvUUID). It's the fourth listed.
Your Logical Volume is revertible, so enter:
diskutil coreStorage revert lvUUID to revert your CoreStorage Volume to a standard volume. In your case this is:
diskutil coreStorage revert 54E92188-CDD5-44AE-9D58-EF6A5B69D707
This will take a few seconds.
After a successfull conversion enter 'exit' and quit Terminal.
Open 'Disk Utility', hightlight the volume 'Macintosh HD' and check it for errors
Highlight the HDD and expand the volume 'Macintosh HD' to the full possible size (~1 TB)
Quit 'Disk Utility' and reboot to your standard boot volume ('Macintosh HD')

Cannot use Disk Utility to create partition from free space on external USB drive

I think Disk Utility misses a proper EFI partition at the beginning of the disk.

If you don't want to completely erase the drive you should be successful following the steps below:

Open Terminal and enter the following to get an overview:
```
diskutil list
```
The 3 TB disk is your external disk. In the next steps I assume the disk identifier of your external disk is disk1
Get the block size of the external disk:
```
diskutil info disk1 | grep "Device Block Size"
```
In the next steps I assume that the Device Block Size is 512 bytes. If you get another block size (i.e. 4096 bytes) leave a comment.

Get the partition table of the external disk:

sudo gpt -r show /dev/disk1

The result is similar to the output below (your sizes are different though):

       start        size  index  contents
           0           1         PMBR
           1           1         Pri GPT header
           2          32         Pri GPT table
          34      262144      1  GPT part - E3C9E316-0B5C-4DB8-817D-F92DF00215AE
      262178        2014         
      264192  2244603904      2  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
  2244868096  2048002015         
  4292870111          32         Sec GPT table
  4292870143           1         Sec GPT header

Unmount the external disk:
```
diskutil umountDisk /dev/disk1
```

Now add a third partition with

sudo gpt add -b 2244870110 -i 3 -s 1000000000 -t 48465300-0000-11AA-AA11-00306543ECAC disk1

I left some unallocated space (2014 blocks) between partition 2 and 3.

The resulting partition table looks like this then:

       start        size  index  contents
           0           1         PMBR
           1           1         Pri GPT header
           2          32         Pri GPT table
          34      262144      1  GPT part - E3C9E316-0B5C-4DB8-817D-F92DF00215AE
      262178        2014         
      264192  2244603904      2  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
  2244868096        2014         
  2244870110  1000000000      3  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
  3244870110  1048000001         
  4292870111          32         Sec GPT table
  4292870143           1         Sec GPT header

You should choose a bigger size than 1000000000 blocks. The number of blocks has to be dividable through 8. The max size in my case would have been 2048000000 (1000000000 + 1048000001).

Now format the new partition with a file system and name the volume (in the example below Backup):
```
sudo newfs_hfs -J -v "Backup" /dev/disk1s3
```

Mount the volume and verify it:

diskutil mount /dev/disk1s3
diskutil verifyVolume /dev/disk1s3

Best Answer

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