Time Machine local snapshots using up all disk space

The interaction with iCloud Dirve seems to also have a lot to do with some of my issues. I was up to 200gb free yesterday. Now I'm down to 110gb without having added new large files. TZ only has one local snapshot (which is oddly low) which is almost 24 hours old. It only uses about 10gb, and this is the same as the purgable amount in shown in Disk Utility. So were did I lose this nearly 90gb of memory to? I went searching and found it here:

/Users/<user>/Library/Caches/CloudKit/com.apple.bird/<hash>/MMCS/ClonedFiles

Based on the sizes of the large files I see in this directory, they are the large video files that I had copied to the iCloud Drive, and then did a "remove download" on once they were uploaded. I also see them in my wife's account. I had noticed a couple of days ago that even though from that account the iCloud Drive was never accessed, downloads happened anyway. I had removed all the downloads and then yesterday noticed a couple came back, so I turned off iCloud Drive since her account doesn't need it on. So iCloud Drive is now disabled, yet has 40gb in this cache still. I wonder if these are "orphaned" caches that iCloud Drive doesn't know it no longer needs.

Luis Sequeira1 wrote:

Open Disk Utility.

You should see all the local snapshots in there. Select and click the "-" button to delete.

My question was not how to delete the snapshots. In fact I think I made it clear that I had deleted them. My question is how to prevent snapshots from holding on to references to large files that have been deleted, and doing so even as my disk runs out of space. I'm getting app crashes and the inability to even save small files. Going into Disk Utility to delete the snapshots (which I have been doing) to fix this should not be something a user needs to do. I would disable local snapshots if I could. They serve me no purpose and cause too much grief.

Luis Sequeira1 wrote:

Before anything else: running your system with about 15GB free is dangerous. Any drive needs to have at least 15-20% free space, especially if it is the system drive. I would not want to save anything, or use the drive if it is that full.

That said, I am not convinced that snapshots are the problem here. Besides the matter with snapshots, it happens that macOS is very eager to keep disk space as "available" instead of "free", which is unfortunate.

It's definitely the snapshots. I've gone in and looked at their contents and found the large files that have otherwise been deleted from the disk.

I'm not attempting to run with 15gb free. I try to keep a lot more than that free (100 to 200gb) by aggressively deleting these large files. But TZ snapshots prevent the space from actually getting freed.

It's odd that when both times I ran into this, I had 15gb free and at that point macOS basically decided I could no longer do disk writes. I couldn't even touch a file to create it. Although snapshots are holding onto a lot of disk space at this point, it seems that there is also something else going. The disk is in an an APFS container that also has two other volumes (they weren't mounted). Could that be resulting in some sort of 15gb reservation that prevents my main disk from accessing that free space.

It's also odd that macOS is not purging the purge-able disk usage when this situation arises.

In the past hour the amount of free and purgeable space increased by 40gb (I've done nothing to instigate this), which is the same size as the iCloud Drive cache files for the account that still has iCloud Drive enabled. The files are still in the cache. Seems some accounting was done to suddenly start including them in the free and purgeable sizes, but not to actually get rid of them. For the account that has disabled iCloud Drive, the files are also still present, but haven't been added back into the free and purgeable sizes yet.