Trying to delete non-Time-Machine snapshot

[DominikHoffmann]

I am trying to make space on my limited-size SSD (512 GB). From having run the backup software Arq in the past I see an Arq snapshot occupying 106 GB. I would like to delete it, in order to reclaim that space. To wit:

user@host ~ % tmutil listlocalsnapshots /
Snapshots for disk /:
com.apple.TimeMachine.2023-05-16-161821.local
com.apple.TimeMachine.2023-05-16-175912.local
com_haystacksoftware_arqagent_A21DCAA3-6CF2-4989-8B21-6CEF84721A97_1

The last one is the one I am talking about. The first two are the local Time Machine backup that will always exist, whether you have a Time Machine backup volume, or not. I want to delete the one generated by Arq. Let’s see, what happens:

user@host ~ %  sudo tmutil deletelocalsnapshots com_haystacksoftware_arqagent_A21DCAA3-6CF2-4989-8B21-6CEF84721A97_1
Password: ****************
com_haystacksoftware_arqagent_A21DCAA3-6CF2-4989-8B21-6CEF84721A97_1 is not a valid disk

Why is that?

What would I do to get rid of that snapshot? Arq has already been uninstalled. This computer is on Big Sur, which as far as it will go (without OpenCore Legacy Patcher).

 

[DominikHoffmann]

I ran this command:

sudo tmutil thinlocalsnapshots / 42949672960 4

The number “42949672960” is the number of bytes I would like to get freed. “4” is the urgency level on a scale from 1 to 4. Here’s the output:

user@host ~ % sudo tmutil thinlocalsnapshots / 42949672960 4
Password:
Thinned local snapshots:
com_haystacksoftware_arqagent_A21DCAA3-6CF2-4989-8B21-6CEF84721A97_1

I reclaimed, it seems, exactly the amount occupied by the snapshot “com_haystacksoftware_arqagent_A21DCAA3-6CF2-4989-8B21-6CEF84721A97_1”, because now it’s gone from the snapshot listing:

user@host ~ % tmutil listlocalsnapshots /
Snapshots for disk /:
com.apple.TimeMachine.2023-05-16-161821.local
com.apple.TimeMachine.2023-05-16-175912.local
com.apple.TimeMachine.2023-05-16-185919.local
com.apple.TimeMachine.2023-05-16-200055.local
com.apple.TimeMachine.2023-05-16-210102.local
com.apple.TimeMachine.2023-05-16-220107.local
com.apple.TimeMachine.2023-05-16-230113.local

Credit: Der Flounder.