The other day it wouldn't even allow me to remove or truncate files, because it was running out of space. I was annoyed: How would you free space if you can't

The other day it wouldn't even allow me to remove or truncate files, because it was running out of space. I was annoyed: How would you free space if you can't remove anything. There wasn't any snapshot of those files, but I was able to free space by removing another snapshot (which I wanted to keep, but never mind...).