How can I erase an APFS Snapshot on my StartUp Container Disk to save space ?

KostasTournas wrote:

I thank you both for your help.

Still my start up disc has 16Gb of space that I need.

T̶h̶i̶s̶ ̶s̶p̶a̶c̶e̶ ̶w̶a̶s̶ ̶c̶r̶e̶a̶t̶e̶d̶ ̶l̶a̶s̶t̶ ̶n̶i̶g̶h̶t̶ ̶(̶I̶ ̶d̶o̶n̶t̶ ̶k̶n̶o̶w̶ ̶h̶o̶w̶)̶ ̶a̶l̶m̶o̶s̶t̶ ̶a̶ ̶m̶o̶n̶t̶h̶ ̶a̶f̶t̶e̶r̶ ̶I̶ ̶i̶n̶s̶t̶a̶l̶l̶e̶d̶ ̶B̶i̶g̶ ̶S̶u̶r̶e̶.̶

If it is important (and not eraseble) for the Software why wasn't needed from the start of installation of Big Sure ?

https://discussions.apple.com/content/attachment/b9c453cf-77e8-403c-bc63-d6fb6040fba8

I know I trouble some of you but I must find a way of geting back those 16Gb.

KostasTournas—You are wrong.

I do not know how else to say it...You can not. Full stop. This was all explained above

It is the new normal.

ex. of the new normal including the SSV (snapshot). These are your System files.

Look to clear up storage space in other ways, ex:

Empty your Trash — Delete files and folders on Mac - Apple Support

https://support.apple.com/guide/mac-help/delete-files-and-folders-on-mac-mchlp1093/mac

How to free up storage space on your Mac - Apple Support 

https://support.apple.com/en-us/HT206996

See used and available storage space on your Mac

https://support.apple.com/guide/system-information/see-available-storage-space-syspf9b375b9/10.14/mac/10.15

User tip: "Other and What Can I Do About It ?

https://discussions.apple.com/docs/DOC-5142

Try something like OmniDiskSweeper for a GUI to get a good look at itemized file size and location:

OmniDiskSweeper http://www.omnigroup.com/more

Your problem seems to stem from not understanding how Big Sure works, and what an APFS Snapshot actually is.

An APFS Snapshot takes up virtually no space. It isn't a copy. It is references to actual storage, not the storage itself. You could probably make a few hundred snapshots without seeing any noticeable difference in storage.

The com.apple.whatever snapshot is a "sealed" snapshot that cannot be modified. It isn't taking up any space as noted above.

KostasTournas wrote:

How can I erase an APFS Snapshot on my StartUp Container Disk to save space ?

Not sure what a start up Container Disk is...(?)

With the new macOS Big Sur the Macintosh HD uses a snapshot as the signed system volume (SSV) —you are not going to delete that.

You see more of the big picture if you choose Disk Utility>View>Show all Devices

Big Sur uses a “snapshot” of the current system for its Signed System Volume, as you see in the list. This is the new normal as well. This would be the 'Macintosh HD'

ex from the Terminal.app

diskutil list internal     

/dev/disk0 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *1.0 TB disk0

1: EFI ⁨EFI⁩ 314.6 MB disk0s1

2: Apple_APFS ⁨Container disk1⁩ 1.0 TB disk0s2

/dev/disk1 (synthesized):

#: TYPE NAME SIZE IDENTIFIER

0: APFS Container Scheme - +1.0 TB disk1

Physical Store disk0s2

1: APFS Volume ⁨Macintosh HD⁩ 14.9 GB disk1s1

2: APFS Snapshot ⁨com.apple.os.update-...⁩ 14.9 GB disk1s1s1

3: APFS Volume ⁨Macintosh HD - Data⁩ 279.7 GB disk1s2

4: APFS Volume ⁨Preboot⁩ 281.5 MB disk1s3

5: APFS Volume ⁨Recovery⁩ 655.5 MB disk1s4

6: APFS Volume ⁨VM⁩ 1.1 GB disk1s5

ref:

About the read-only system volume in macOS Catalina /Big Sur- Apple ...

https://support.apple.com/en-us/HT210650

If you are trying to free Disk space—

How to free up storage space on your Mac - Apple Support

https://support.apple.com/en-us/HT206996

KostasTournas wrote:

Inside my StartUp Disc, a Container Disc 1 is created, where a file of 16Gb exists.

This file wasn't there when I first installed Big Sure...it uppeared last night out of the blue.

So this file gets a lot of space on my StartUp Disc and I want to erase it.

I've tried all possible edit mooves fron the Disc Utility, but it appears, that a new Terminal Code is needed to fix this.

Anyone here or from Apple having an answer or suggestion ?

Post the out put from the Terminal.app copy and paste:

diskutil list internal     

Barney-15E is right, that the snapshot is the current update version of the 15Gb Sealed System volume (SSV). You cannot delete this volume.