diff --git a/man/man5/vdev_id.conf.5 b/man/man5/vdev_id.conf.5
index a2d38add4ee0..aaf91825a6c6 100644
--- a/man/man5/vdev_id.conf.5
+++ b/man/man5/vdev_id.conf.5
@@ -92,6 +92,11 @@ before a generic mapping for the same slot.
 In this way a custom mapping may be applied to a particular channel
 and a default mapping applied to the others.
 .
+.It Sy zpad_slot Ar digits
+Pad slot numbers with zeros to make them
+.Ar digits
+long, which can help to make disk names a consistent length and easier to sort.
+.
 .It Sy multipath Sy yes Ns | Ns Sy no
 Specifies whether
 .Xr vdev_id 8
@@ -122,7 +127,7 @@ device is connected to.
 The default is
 .Sy 4 .
 .
-.It Sy slot Sy bay Ns | Ns Sy phy Ns | Ns Sy port Ns | Ns Sy id Ns | Ns Sy lun Ns | Ns Sy ses
+.It Sy slot Sy bay Ns | Ns Sy phy Ns | Ns Sy port Ns | Ns Sy id Ns | Ns Sy lun Ns | Ns Sy bay_lun Ns | Ns Sy ses
 Specifies from which element of a SAS identifier the slot number is
 taken.
 The default is
@@ -138,6 +143,9 @@ use the SAS port as the slot number.
 use the scsi id as the slot number.
 .It Sy lun
 use the scsi lun as the slot number.
+.It Sy bay_lun
+read the slot number from the bay identifier and append the lun number.
+Useful for multi-lun multi-actuator hard drives.
 .It Sy ses
 use the SCSI Enclosure Services (SES) enclosure device slot number,
 as reported by
diff --git a/udev/vdev_id b/udev/vdev_id
index 7b5aab141997..5897fea3ed66 100755
--- a/udev/vdev_id
+++ b/udev/vdev_id
@@ -124,6 +124,7 @@ TOPOLOGY=
 BAY=
 ENCL_ID=""
 UNIQ_ENCL_ID=""
+ZPAD=1
 
 usage() {
 	cat << EOF
@@ -154,7 +155,7 @@ map_slot() {
 	if [ -z "$MAPPED_SLOT" ] ; then
 		MAPPED_SLOT=$LINUX_SLOT
 	fi
-	printf "%d" "${MAPPED_SLOT}"
+	printf "%0${ZPAD}d" "${MAPPED_SLOT}"
 }
 
 map_channel() {
@@ -430,6 +431,15 @@ sas_handler() {
 		d=$(eval echo '$'{$i})
 		SLOT=$(echo "$d" | sed -e 's/^.*://')
 		;;
+	"bay_lun")
+		# Like 'bay' but with the LUN number appened. Added for SAS 
+		# multi-actuator HDDs, where one physical drive has multiple
+		# LUNs, thus multiple logical drives share the same bay number
+		i=$((i + 2))
+		d=$(eval echo '$'{$i})
+		LUN="-lun$(echo "$d" | sed -e 's/^.*://')"
+		SLOT=$(cat "$end_device_dir/bay_identifier" 2>/dev/null)
+		;;
 	"ses")
 		# look for this SAS path in all SCSI Enclosure Services
 		# (SES) enclosures
@@ -460,7 +470,7 @@ sas_handler() {
 		if [ -z "$CHAN" ] ; then
 			return
 		fi
-		echo "${CHAN}"-"${JBOD}"-"${SLOT}${PART}"
+		echo "${CHAN}"-"${JBOD}"-"${SLOT}${LUN}${PART}"
 	else
 		CHAN=$(map_channel "$PCI_ID" "$PORT")
 		SLOT=$(map_slot "$SLOT" "$CHAN")
@@ -468,7 +478,7 @@ sas_handler() {
 		if [ -z "$CHAN" ] ; then
 			return
 		fi
-		echo "${CHAN}${SLOT}${PART}"
+		echo "${CHAN}${SLOT}${LUN}${PART}"
 	fi
 }
 
@@ -748,6 +758,8 @@ if [ -z "$BAY" ] ; then
 	BAY=$(awk '($1 == "slot") {print $2; exit}' "$CONFIG")
 fi
 
+ZPAD=$(awk '($1 == "zpad_slot") {print $2; exit}' "$CONFIG")
+
 TOPOLOGY=${TOPOLOGY:-sas_direct}
 
 # Should we create /dev/by-enclosure symlinks?