{ config, lib, pkgs, ... }: with lib; { options.hardware.usbStorage.manageStartStop = mkOption { type = types.bool; default = true; description = lib.mdDoc '' Enable this option to gracefully spin-down external storage during shutdown. If you suspect improper head parking after poweroff, install `smartmontools` and check for the `Power-Off_Retract_Count` field for an increment. ''; }; config = mkIf config.hardware.usbStorage.manageStartStop { services.udev.extraRules = '' ACTION=="add|change", SUBSYSTEM=="scsi_disk", DRIVERS=="usb-storage", ATTR{manage_system_start_stop}="1" ''; }; }