Disable local snapshots in High Sierra with APFS

There is a terminal command to turn off local snapshots: sudo tmutil disablelocal

It's from this Apple Developer's page: https://forums.developer.apple.com/thread/81171

If you don't have a Developer's account here's what it says:

Is there a way to turn on and off the local TM snapshots? On Sierra, there was "sudo tmutil enablelocal" but it's no longer supported.

Correct Answer by tclementdev on Jun 30, 2017 9:08 AM

1. Yes, this is similar to the current local snapshots implementation. I think it is represented in Disk Utility or About this Mac as "backup" or "purgeable" disk space. It's supposed to be automatically reclaimed as needed. And I think there was a trick where the Finder would display the free size of a disk as the actual free size + the purgeable size, so users wouldn't be confused as much.

But Snapshots (and clones) can be way more confusing, for example deleting files will not necessarily give you back disk space, if the files data is still referenced somewhere in clones or snapshots. So it's quite important to harvest snapshots periodically.

The 'tmutil listlocalsnapshots /' command will list all the snapshots but will not tell you how much size they occupy. By that, I mean the size that only they are referencing (.i.e. the size you would get back by deleting the snapshots). But that can be done, I just don't think Apple is showing that information anywhere for now. You're not supposed to have to worry about all this if Time Machine does its job correctly of managing the snapshots.

2. As far as I know, APFS snapshots are only exposed through the Time Machine local snapshots feature. That being said, you don't need to configure any backup disk or enable automatic backups to be able to create local snapshots (but they will be created for you as part of the automatic backups of Time Machine). I think local snapshots and regular backups will just be shown together when you browse the Time Machine history of your disk as is currently the case.

3. Just enable the "Back Up Automatically" checkbox from System Preferences > Time Machine. This will ask you to configure a backup disk. I don't think there is currently a way to have only local snapshots being created automatically, without also configuring a regular backup disk.