diff --git a/xCAT-server/share/xcat/install/scripts/pre.sles b/xCAT-server/share/xcat/install/scripts/pre.sles
index e6e77ec47..768734cb7 100644
--- a/xCAT-server/share/xcat/install/scripts/pre.sles
+++ b/xCAT-server/share/xcat/install/scripts/pre.sles
@@ -113,11 +113,50 @@ chmod 755 /tmp/bar.awk
 
 /tmp/bar.awk &
 /tmp/foo.awk >/tmp/foo.log 2>&1 &
+shopt -s nullglob
+for disk in /dev/vd*[^0-9];do
+	if [ -z "$firstdirectdisk" ]; then firstdirectdisk=$disk; fi #remember first disk as a guess of medium resort
+	eddname=$(/lib/udev/edd_id $disk 2> /dev/null)
+	if [ ! -z "$eddname" -a "$eddname" = "int13_dev80" ]; then
+		instdisk=$disk
+		break
+	fi
+done
+if [ -z "$instdisk" ]; then
+	for disk in /dev/sd*[^0-9]; do
+		eddname=$(/lib/udev/edd_id $disk 2> /dev/null)
+		if [ ! -z "$eddname" -a "$eddname" = "int13_dev80" ]; then
+			instdisk=$disk
+			break
+		fi
+		currdriver=`udevadm info --attribute-walk --name $disk |grep DRIVERS|grep -v '""'|grep -v '"sd"'|head -n 1|sed -e 's/[^"]*"//' -e 's/"//'`
+		case "$currdriver" in 
+		"ata_piix4"|"PMC MaxRAID"|"ahci"|"megaraid_sas") #certainly direct
+			if [ -z "$firstdirectdisk" ]; then firstdirectdisk=$disk; fi #remember first disk as a guess of medium resort
+			;;
+		"mptsas"|"mpt2sas") #*PROBABLY* not SAN, but SAS SAN is possible
+			if [ -z "$probablyfirstdirectdisk" ]; then probablyfirstdirectdisk=$disk; fi #remember first disk as a guess of medium resort
+			;;
+		*)
+			if [ -z "$firstdisk" ]; then firstdisk=$disk; fi #remember first disk as a guess of medium resort
+			;;
+		esac
+	done
+fi
+if [ -z "$instdisk" ]; then
+	if [ ! -z "$firstdirectdisk" ]; then 
+		instdisk=$firstdirectdisk 
+	elif [ ! -z "$probablyfirstdirectdisk" ]; then
+		instdisk=$probablyfirstdirectdisk 
+	elif [ ! -z "$firstdisk" ]; then
+		instdisk=$firstdisk 
+	fi
+fi
 
 if [ -d /sys/firmware/efi ]; then
-	sed -e 's!<device>XCATPARTITIONHOOK</device>!<device>/dev/sda</device><partitions config:type="list"><partition><filesystem config:type="symbol">vfat</filesystem><mount>/boot/efi</mount><size>128mb</size></partition><partition><mount>swap</mount><size>auto</size></partition><partition><mount>/</mount><size>auto</size></partition></partitions>!' /tmp/profile/autoinst.xml > /tmp/profile/modified.xml
+	sed -e 's!<device>XCATPARTITIONHOOK</device>!<device>'$instdisk'</device><partitions config:type="list"><partition><filesystem config:type="symbol">vfat</filesystem><mount>/boot/efi</mount><size>128mb</size></partition><partition><mount>swap</mount><size>auto</size></partition><partition><mount>/</mount><size>auto</size></partition></partitions>!' /tmp/profile/autoinst.xml > /tmp/profile/modified.xml
 else
-	sed -e 's!<device>XCATPARTITIONHOOK</device>!<device>/dev/sda</device>!' /tmp/profile/autoinst.xml > /tmp/profile/modified.xml
+	sed -e 's!<device>XCATPARTITIONHOOK</device>!<device>'$instdisk'</device>!' /tmp/profile/autoinst.xml > /tmp/profile/modified.xml
 fi
 ]]>