diff --git a/agent/src/com/cloud/agent/resource/computing/LibvirtComputingResource.java b/agent/src/com/cloud/agent/resource/computing/LibvirtComputingResource.java
index a508e4ea29b..e5319d555d8 100644
--- a/agent/src/com/cloud/agent/resource/computing/LibvirtComputingResource.java
+++ b/agent/src/com/cloud/agent/resource/computing/LibvirtComputingResource.java
@@ -2257,12 +2257,8 @@ public class LibvirtComputingResource extends ServerResourceBase implements Serv
 					disk.defISODisk(volPath);
 				}
 			} else {
-				int devId = 0;
-				if (volume.getType() == VolumeType.ROOT) {
-					devId = 0;
-				} else {
-					devId = 1;
-				}
+				int devId = (int)volume.getDeviceId();
+				
 				disk.defFileBasedDisk(volume.getPath(), devId, diskBusType, DiskDef.diskFmtType.QCOW2);
 			}
 
diff --git a/agent/src/com/cloud/agent/resource/computing/LibvirtVMDef.java b/agent/src/com/cloud/agent/resource/computing/LibvirtVMDef.java
index f6c78e9155d..48cf88a5fc7 100644
--- a/agent/src/com/cloud/agent/resource/computing/LibvirtVMDef.java
+++ b/agent/src/com/cloud/agent/resource/computing/LibvirtVMDef.java
@@ -303,7 +303,12 @@ public class LibvirtVMDef {
 			_bus = bus;
 
 		}
+		/*device id starting from 0, but iso is 3*/
 		private String getDevLabel(int devId, diskBus bus) {
+			if ( devId >= 2 ) {
+				devId++;
+			}
+			
 			char suffix = (char)('a' + devId);
 			if (bus == diskBus.SCSI) {
 				return "sd" + suffix;
@@ -311,7 +316,9 @@ public class LibvirtVMDef {
 				return "vd" + suffix;
 			}
 			return "hd" + suffix;
+			
 		}
+		
 		public void defFileBasedDisk(String filePath, int devId, diskBus bus, diskFmtType diskFmtType) {
 			
 			_diskType = diskType.FILE;