Understanding APFS (trying to, that is)

Not sure if this is too involved an inquiry for this forum, but here goes …

Attached is a mapping of one of my system drives.
I have always been one to install numerous volumes on a drive to either keep old things going, or try new systems.
I’d like to keep my High Sierra, Mojave, and Monterey systems in place but add a Ventura volume as an experiment before upgrading the Monterey volume to Ventura

On this particular drive I did not create separate partitions, but multiple APFS volumes.
The sizing and free space notes still confuses me a bit … to cut to the chase I have attached screenshot and mapping of the drive.
Q1: are the old Mac OS 11.1 volumes just old Big Sur snapshots? Can they be deleted i.e. reformatted at this point?
Q2: notwithstanding the dubious nature of adding so many volumes to one drive, might, should I utilize the more capacious free space (458GB) on the Mojave “volume”

Technically I think minimum of 60GB might suffice for a Ventura volume

Anyway if anybody’s interested LMK
If not I’ll understand :innocent:

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My basic update is: the drive mapping was more understandable booted in HIgh Sierra, so I simply added a volume to the Container in lieu of reformatting any particular volume

I find that more info is better. Maybe these two commands in the terminal will help you find answers?

df -h
Filesystem       Size   Used  Avail Capacity iused      ifree %iused  Mounted on
/dev/disk3s1s1  926Gi  8.4Gi  440Gi     2%  355384 4292527517    0%   /
devfs           201Ki  201Ki    0Bi   100%     694          0  100%   /dev
/dev/disk3s6    926Gi   20Ki  440Gi     1%       0 4613527360    0%   /System/Volumes/VM
/dev/disk3s2    926Gi  4.4Gi  440Gi     1%     875 4613527360    0%   /System/Volumes/Preboot
/dev/disk3s4    926Gi   23Mi  440Gi     1%      55 4613527360    0%   /System/Volumes/Update
/dev/disk1s2    500Mi  6.0Mi  480Mi     2%       1    4914840    0%   /System/Volumes/xarts
/dev/disk1s1    500Mi  6.2Mi  480Mi     2%      29    4914840    0%   /System/Volumes/iSCPreboot
/dev/disk1s3    500Mi  3.1Mi  480Mi     1%      52    4914840    0%   /System/Volumes/Hardware
/dev/disk3s5    926Gi  240Gi  440Gi    36% 2735016 4613527360    0%   /System/Volumes/Data
/dev/disk3s8    926Gi   76Gi  440Gi    15%    6926 4613527360    0%   /Volumes/Diverse
/dev/disk3s9    926Gi  157Gi  440Gi    27%   70004 4613527360    0%   /Volumes/Hot
/dev/disk3s7    926Gi  1.2Mi  440Gi     1%     169 4613527360    0%   /Volumes/OS-2
map auto_home     0Bi    0Bi    0Bi   100%       0          0  100%   /System/Volumes/Data/home
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            9.1 GB     disk3s1
   2:              APFS Snapshot com.apple.os.update-... 9.1 GB     disk3s1s1
   3:                APFS Volume Preboot                 4.7 GB     disk3s2
   4:                APFS Volume Recovery                804.4 MB   disk3s3
   5:                APFS Volume Data                    257.6 GB   disk3s5
   6:                APFS Volume VM                      20.5 KB    disk3s6
   7:                APFS Volume OS-2                    1.2 MB     disk3s7
   8:                APFS Volume Diverse                 81.1 GB    disk3s8
   9:                APFS Volume Hot                     168.7 GB   disk3s9
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Howard Oakley (via his Eclectic Light Co site) has posted articles describing the various layouts of storage volumes on macOS over the years:

It’s a lot of reading, but it does explain what is going on and how these layouts have changed over the years since the introduction of APFS.


I guess I will need to review the volume mapping with the Terminal
as Disk Utility does not seem to detail all the various hidden volumes.
I am having a bit of a hard time getting clarity at eclecticlight on why Big Sur
installed 3 nominal versions of itself. Per my image, Big Sur installed the main volume (which now runs Monterey, btw) and one and then another “shadow” volume. The first at the first install, and then another shadow volume at one of Big Sur’s major updates. Interestingly both tagged as
Mac OS 11.1 … That’s why I was wondering if they were Big Sur’s version of snapshots …


Simply run the command df in the terminal and you’ll see all mounted volumes and where they’re mapped from. It’s a totally safe command, you don’t risk deleting any data.

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