smartd: set drive timeout

nixos/modules/services/monitoring/smartd.nix

@@ -81,13 +81,32 @@ let
         description = "Options that determine how smartd monitors the device.";
       };
 
+      timeout = mkOption {
+        default = -1;
+        example = "70";
+        type = types.int;
+        description = ''
+          Set SCT Error Recovery Control timeout in deciseconds for use in raid configurations.
+
+          Values are as follows:
+            -1 = do not touch, leave at default
+             0 = disable SCT ERT
+            70 = default in consumer drives (7 seconds)
+
+          Maximum is disk dependant but probably 60 seconds.
+        '';
+      };
+
     };
 
   };
 
-in
+  deviceTimeout = d:
+    lib.optionalString (d.timeout > -1) ''
+      ${pkgs.smartmontools}/bin/smartctl -l scterc,${d.timeout},${d.timeout} --silent errorsonly ${d.device}
+    '';
 
-{
+in {
   ###### interface
 
   options = {
@@ -222,7 +241,13 @@ in
 
       path = [ pkgs.nettools ]; # for hostname and dnsdomanname calls in smartd
 
-      serviceConfig.ExecStart = "${pkgs.smartmontools}/sbin/smartd --no-fork --configfile=${smartdConf}";
+      serviceConfig = {
+        ExecStartPre = ''
+          ${concatMapStringsSep "\n" deviceTimeout cfg.devices}
+        '';
+        ExecStart = "${pkgs.smartmontools}/sbin/smartd --no-fork --configfile=${smartdConf}";
+      };
+
     };
 
   };