The Apple support article “About Time Machine local snapshots” says that “if less than 20% of the total storage space on your startup drive is available, Time Machine removes local snapshots, starting with the oldest, until you have more than 20% free space.”
If I understand that correctly, that means the local snapshots feature stops working as soon as you fill up 80% of your drive. For a 500GB drive, Time Machine insists on keeping at least 100GB free.
That seems like a lot of space to keep free. I’m not sure why that would be necessary. As a side question: is there any reason why it is specified as a relative percentage of the drive’s size rather than as an absolute number?
Main question: is there any way to decrease this from 20% to, for example, just 10% (so 50GB for a 500GB drive)?