The folder only stops if the storage device that holds the database is past the threshold (not the device that holds the database). Stopping the folder and pulling the plug for others is the right thing todo in that scenario, as it prevents others from downloading files and sending index updates which you cannot accept (as your disk is full), leading to corruption. Device B finishing a download is not for free in terms of A, as A has to record the fact B now has the file, it’s version and so on, which requires disk space.