diff --git a/xCAT-server/share/xcat/install/scripts/pre.rh b/xCAT-server/share/xcat/install/scripts/pre.rh
index b37399340..dac9f1fbe 100644
--- a/xCAT-server/share/xcat/install/scripts/pre.rh
+++ b/xCAT-server/share/xcat/install/scripts/pre.rh
@@ -218,6 +218,12 @@ if [ -z "$instdisk" ]; then
 		instdisk=$firstdisk 
 	fi
 fi
+
+# Could not determine the install disk for whatever reason,
+# try the default /dev/sda
+if [ -z "$instdisk" ]; then
+    instdisk="/dev/sda"
+fi
 		
 
 modprobe ext4 >& /dev/null
diff --git a/xCAT-server/share/xcat/install/scripts/pre.rh.rhel7 b/xCAT-server/share/xcat/install/scripts/pre.rh.rhel7
index f4c713aec..b373a9164 100755
--- a/xCAT-server/share/xcat/install/scripts/pre.rh.rhel7
+++ b/xCAT-server/share/xcat/install/scripts/pre.rh.rhel7
@@ -182,6 +182,12 @@ if [ -z "$instdisk" ]; then
 		instdisk=$firstdisk 
 	fi
 fi
+# Could not determine the install disk for whatever reason,
+# try the default /dev/sda
+if [ -z "$instdisk" ]; then
+    instdisk="/dev/sda"
+fi
+
 modprobe ext4 >& /dev/null
 modprobe ext4dev >& /dev/null
 if grep ext4dev /proc/filesystems > /dev/null; then