I’ve dedicated about 4 TB to back up about 1.6 TB. When I create a new share of that size, and designate it for Time Machine backups, it works fine for a while. Inevitably, the backups start to fail after a few weeks saying either insufficient disk space. Time Machine is supposed to delete old backups and replace them, and it used to.
If I delete the backups from Time Machine, it doesn’t help. The only solution is to delete the share and recreate it. I’m on my 5th iteration, now. Tempted to go back to using a USB connected disk, but want to ask here first.