I needed to shrink a TM partition. I was able to do it because there was some free space available. However, I need to shrink it even further, but Disk Utility says "This container has 586.66 GB used space. Its minimum size is 1.55 TB. Snapshot tidemarks can raise the minimum size above the used size.". How come? There is only 586.66 GB used, so why minimum size is 1.55TB? Why I need to keep 967.38 GB free??
You do not want to use the same drive for Time Machine and other storage.
If you do, then you will lose both when the drive fails.
Personally I use a 2T external drive for Time Machine and nothing else.
Then I use several external SSDs for Clone Backups and Extra Storage.
Because Time Machine needs the extra space for future backups.
Plus you should never use the same drive (partitioned or not) for storing other files.
1 TB extra space? I can't believe this is the reason...
Unless you need the drives that do Video Editing speeds, More and larger drives are not expensive these days. Buy more drives instead of telling Time Machine how to do its business.
Shrinking APFS partition.
