For mdadm's systemd configuration, current systemd KillMode is "none" in following service files, - mdadm-grow-continue@.service - mdmon@.service This "none" mode is strongly againsted by systemd developers (see man 5 systemd.kill for "KillMode=" section), and is considering to remove in future systemd version. As systemd developer explained in disuccsion, the systemd kill process is, 1. send the signal specified by KillSignal= to the list of processes (if any), TERM is the default 2. wait until either the target of process(es) exit or a timeout expires 3. if the timeout expires send the signal specified by FinalKillSignal=, KILL is the default For "control-group", all remaining processes will receive the SIGTERM signal (by default) and if there are still processes after a period f time, they will get the SIGKILL signal. For "mixed", only the main process will receive the SIGTERM signal, and if there are still processes after a period of time, all remaining processes (including the main one) will receive the SIGKILL signal.
