On macOS, the hard drive or the SSD, whichever you have is usually a single disk. You do not partition a disk on a Mac as you would on a PC but that doesn’t necessarily mean you cannot create additional volumes within the same disk on a Mac. You can. In fact, Apple added the ability to create an ççç volume (Apple File System volume) back in High Sierra. Here’s how.
Create an APFS volume
An APFS volume is something that’s best suited for an SSD however, you can create one just as easily for an HDD. The process is the same.
Open Disk Utility and click the Partition button. In the menu that opens, click the ‘Volume’ option.
In the next panel, enter a name for your new volume. As far as creating an APFS volume goes, this is really all you need to do but we’re looking to limit the size of the volume. To do that, click the ‘Size Options’ button on this panel.
In the second panel that opens, you reserve the size for the volume. The reserved size is what the minimum size of the volume will be. Your main disk will never be able to use the space that you allocate to this volume under its reserved size. The second, optional size that you can set for the volume is its Quota. The Quota is the maximum size that the volume can be. If you try and add files to the volume that exceeds this size, you won’t be able to. In the absence of the quota, the volume’s size will change proactively. Click OK, and the volume will be created.
The volume will mount by default.
Delete an APFS volume
To delete an APFS volume, you should unmount/eject it first. To do that, right-click it in the left bar in Finder and select the unmount/eject option. Open Disk Utility again, and right-click the APFS volume you created. Select ‘Delete APFS Volume’, and it will be deleted. All the files in the volume will be gone when you delete it. The storage space that is freed up will be added back to the main disk. The space will basically be freed up. Once you delete the volume, there isn’t any getting it back and your files are gone.
You can create as many APFS volumes as you want but it’s always a good idea to limit their size.