How to merge APFS volumes and regain "free space"?

P. Phillips wrote:

Part of the overall issue is the 77.9 GB of Unallocated Space that is not contained in any Container.

Yes - that can easily be reclaimed. Here is what would need to be done:

1. If any APFS volumes exist in the 500 MB container, mount those volumes and transfer out any content that they hold.
2. Open Disk Utility.
3. Select View -> Show All Devices.
4. Select the internal SSD and click Partition. If prompted to add a volume instead, click Partition again to confirm your intent.
5. Delete the 500 MB APFS Container.
6. Delete the 77.9 GB slice labelled as "Free Space". This will return all of that space to the main APFS container on disk0s2 (synthesized as disk3).
7. Click Apply to apply the changes.

Not sure how you got here.

You have not one but two APFS Containers, one of which is a mere 500MB, and then you have that free space.

What do you see in the Disk Utility GUI interface, after selecting View->Show All Devices?

It looks as if there was something weird done to this drive. In the end, probably a full backup followed by an erase of the whole drive and reinstall may be necessary.

Lean towards the suggestion above via @ Luis Sequeira1.

Depending on if this is an Apple Silicon or Intel machine >>

Scorched Earth Method 

This method will WIPE ALL Data and there is No Recovery - Period.

To perform this action will require booting from a Bootable Installer. 

The Bootable Installer can Only be performed on an Apple Computer 

This will have to be performed from a Qualifying Computer to run the version of macOS to be made on the Bootable Installer.

Example : Bootable Installer of Monterey would have to be done on a computer that Qualifies to run Monterey.

Notation: If the computer being used to perform this action is Too New or Too Old to qualify to run the version of macOS - this computer can not be used.

Alternative is, to gain access to a Qualifying Apple Computer from a family member, friend or associate.

Once that is done read on for preparing the Destination computer  >>

Only works on Intel Based Apple Computers.

Extra Special Notation regarding the Touch ID equipped Apple Computer.

About Startup Security Utility and Must Enable from Recovery Mode the ability to boot from External Drive Before Attempting 

1 - Shutdown computer and disconnect all external drive Except the newly created Bootable Installer.

2- Restart and immediately hold the OPTION key until the Startup Manager appears and choose the USB Drive. 

3 - It will present options >> Disk Utilities >> View >> View ALL attached Drives. 

4 - Choose the Upper Most Drive ( not the volumes indented and list below ).

5 - The drive normally is called Apple Media or Apple SSD - that is the drive to Erase and format as APFS with the GUID Partition Map. This applies to macOS 10.14 Mojave and above. 

6 - Once that is done >> backup out of Disk Utilities and choose install macOS. 

7 - Follow the prompts and it may automatically reboot several time. 

8 - Upon a final reboot - Setup Assist will present with the newer version of macOS.

As @ Luis S ( 👍 ) has so correctly identified where the issue is, the next step is to get the extra Volume and used space back and usable.

Any thoughts on this ?

Something to consider carefully.

Step 4 <<<< >>>> Restore the firmware, erase all data and reinstall the latest version of recoveryOS and macOS

P. Phillips wrote:

As @ Luis S ( 👍 ) has so correctly identified where the issue is, the next step is to get the extra Volume and used space back and usable.

Any thoughts on this ?

Something to consider carefully.

Step 4 <<<< >>>> Restore the firmware, erase all data and reinstall the latest version of recoveryOS and macOS

That would be my choice since it will restore everything to factory defaults and correctly erase (aka partition & format) the internal SSD correctly since an M1 Mac has some special areas that should not be deleted and can only be created using the "Restore" firmware option. There are too many unknowns here for any other option in my opinion.

Make sure to have a good backup before attempting this procedure since it will destroy all data on this laptop.

You should always have frequent and regular backups of your computer and all external media (including the cloud) which contains important & unique data.

bumbleben0 wrote:

Reinstalling macOS didn't help, since erasing the disk only erased the portion that wasn't already marked as "free space." Sorry for not clarifying before, but I have a MacBook Air with M1.

How did you go about reinstalling? In this case, reinstalling from Recovery is not going to do it, because the Recovery partition itself is in the drive that you meant to erase.

You should create a bootable installer on a thumb drive, boot from it, and erase the whole drive, not just the system volume.

Hi bumbleben0,

Not sure why everyone else is recommending nuking everything and starting over, but can you please show what's inside the 500 MB APFS container? (disk4 in your screenshot)

If you don't need it, you could use the Disk Utility GUI to delete the 500 MB container, then resize your real container (166 GB) back to full size.

Part of the overall issue is the 77.9 GB of Unallocated Space that is not contained in any Container.