FYI, one fine distinction not directly discussed in that Eclectic Light article (it's assumed as background knowledge) is that ever since the debut of the APFS filesystem, Apple has increasingly been using APFS volume groups (sometimes referred to as containers). Any partition formatted as APFS is actually an APFS volume group, containing one or more APFS volumes.
This might sound like a scheme for sub-partitioning a partition, and that's somewhat true, but there's a key difference between partitions and APFS volume groups: the volume group's storage is shared between all the APFS volumes in the group. Each individual APFS filesystem dynamically grows and shrinks on the fly as files are created or deleted, without need to go through an explicit filesystem resize operation.
Your system and data volumes are members of the same APFS volume group, and therefore effectively part of the same partition.
If you want to see the real structure, open Terminal.app and type
diskutil list:
Code:
% diskutil list
/dev/disk0 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *1.0 TB disk0
1: Apple_APFS_ISC Container disk1 524.3 MB disk0s1
2: Apple_APFS Container disk3 994.7 GB disk0s2
3: Apple_APFS_Recovery Container disk2 5.4 GB disk0s3
/dev/disk3 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +994.7 GB disk3
Physical Store disk0s2
1: APFS Volume Macintosh HD 11.2 GB disk3s1
2: APFS Snapshot com.apple.os.update-... 11.2 GB disk3s1s1
3: APFS Volume Preboot 7.1 GB disk3s2
4: APFS Volume Recovery 1.0 GB disk3s3
5: APFS Volume Macintosh HD - Data 615.3 GB disk3s5
6: APFS Volume VM 20.5 KB disk3s6
My SSD is disk0, and it has three partitions, each an APFS container.
- disk0s1 is Apple_APFS_ISC, a container for firmware and other boot data required on Apple Silicon Macs.
- disk0s2 is the main OS container, and the only one mounted at present.
- disk0s3 is the recoveryOS container, a backup operating system that can reinstall macOS if the main container dies for some reason.
The main partition, disk0s2, has its APFS container presented as a "synthesized" disk3. All the volumes in disk3 (in order, system, system volume snapshot, preboot, recovery, data, and VM aka swap) share the space of the 994.7GB disk0s2 partition.
eclecticlight.co
