diff --git a/tuned/plugins/plugin_disk.py b/tuned/plugins/plugin_disk.py
index 18cb0b6d..1438e354 100644
--- a/tuned/plugins/plugin_disk.py
+++ b/tuned/plugins/plugin_disk.py
@@ -101,20 +101,18 @@ def _init_devices(self):
 		self._use_hdparm = True
 		self._free_devices = set()
 		self._hdparm_apm_devices = set()
-		self._no_hdparm_apm_devices = set()
 		for device in self._hardware_inventory.get_devices("block"):
 			if self._device_is_supported(device):
 				self._free_devices.add(device.sys_name)
+				if self._use_hdparm and self._is_hdparm_apm_supported(device.sys_name):
+					self._hdparm_apm_devices.add(device.sys_name)
+
 		self._assigned_devices = set()
 
 	def _get_device_objects(self, devices):
 		return [self._hardware_inventory.get_device("block", x) for x in devices]
 
 	def _is_hdparm_apm_supported(self, device):
-		if not self._use_hdparm or device in self._no_hdparm_apm_devices:
-			return False
-		if device in self._hdparm_apm_devices:
-			return True
 		(rc, out, err_msg) = self._cmd.execute(["hdparm", "-C", "/dev/%s" % device], \
 				no_errors = [errno.ENOENT], return_err=True)
 		if rc == -errno.ENOENT:
@@ -124,13 +122,10 @@ def _is_hdparm_apm_supported(self, device):
 		elif rc:
 			log.info("Device '%s' not supported by hdparm" % device)
 			log.debug("(rc: %s, msg: '%s')" % (rc, err_msg))
-			self._no_hdparm_apm_devices.add(device)
 			return False
 		elif "unknown" in out:
 			log.info("Driver for device '%s' does not support apm command" % device)
-			self._no_hdparm_apm_devices.add(device)
 			return False
-		self._hdparm_apm_devices.add(device)
 		return True
 
 	@classmethod
@@ -237,7 +232,7 @@ def _drive_spinning(self, device):
 		return not "standby" in out and not "sleeping" in out
 
 	def _instance_update_dynamic(self, instance, device):
-		if not self._is_hdparm_apm_supported(device):
+		if not device in self._hdparm_apm_devices:
 			return
 		load = instance._load_monitor.get_device_load(device)
 		if load is None:
@@ -320,7 +315,7 @@ def _instance_apply_dynamic(self, instance, device):
 		# At the moment we support dynamic tuning just for devices compatible with hdparm apm commands
 		# If in future will be added new functionality not connected to this command,
 		# it is needed to change it here
-		if not self._is_hdparm_apm_supported(device):
+		if device not in self._hdparm_apm_devices:
 			log.info("There is no dynamic tuning available for device '%s' at time" % device)
 		else:
 			super(DiskPlugin, self)._instance_apply_dynamic(instance, device)
@@ -355,7 +350,7 @@ def _get_elevator(self, device, ignore_missing=False):
 
 	@command_set("apm", per_device=True)
 	def _set_apm(self, value, device, sim, remove):
-		if not self._is_hdparm_apm_supported(device):
+		if device not in self._hdparm_apm_devices:
 			if not sim:
 				log.info("apm option is not supported for device '%s'" % device)
 				return None
@@ -371,7 +366,7 @@ def _set_apm(self, value, device, sim, remove):
 
 	@command_get("apm")
 	def _get_apm(self, device, ignore_missing=False):
-		if not self._is_hdparm_apm_supported(device):
+		if device not in self._hdparm_apm_devices:
 			if not ignore_missing:
 				log.info("apm option is not supported for device '%s'" % device)
 			return None
@@ -395,7 +390,7 @@ def _get_apm(self, device, ignore_missing=False):
 
 	@command_set("spindown", per_device=True)
 	def _set_spindown(self, value, device, sim, remove):
-		if not self._is_hdparm_apm_supported(device):
+		if device not in self._hdparm_apm_devices:
 			if not sim:
 				log.info("spindown option is not supported for device '%s'" % device)
 				return None
@@ -411,7 +406,7 @@ def _set_spindown(self, value, device, sim, remove):
 
 	@command_get("spindown")
 	def _get_spindown(self, device, ignore_missing=False):
-		if not self._is_hdparm_apm_supported(device):
+		if device not in self._hdparm_apm_devices:
 			if not ignore_missing:
 				log.info("spindown option is not supported for device '%s'" % device)
 			return None