diff --git a/api/src/com/cloud/api/commands/UpdateHostCmd.java b/api/src/com/cloud/api/commands/UpdateHostCmd.java
old mode 100644
new mode 100755
index 8648e1164d3..a1901490bce
--- a/api/src/com/cloud/api/commands/UpdateHostCmd.java
+++ b/api/src/com/cloud/api/commands/UpdateHostCmd.java
@@ -32,6 +32,7 @@ import com.cloud.api.BaseCmd.CommandType;
 import com.cloud.api.response.HostResponse;
 import com.cloud.host.Host;
 import com.cloud.user.Account;
+import com.cloud.utils.fsm.NoTransitionException;
 
 @Implementation(description="Updates a host.", responseObject=HostResponse.class)
 public class UpdateHostCmd extends BaseCmd {
@@ -50,7 +51,7 @@ public class UpdateHostCmd extends BaseCmd {
     @Parameter(name=ApiConstants.OS_CATEGORY_ID, type=CommandType.LONG, description="the id of Os category to update the host with")
     private Long osCategoryId;
 
-    @Parameter(name=ApiConstants.ALLOCATION_STATE, type=CommandType.STRING, description="Allocation state of this Host for allocation of new resources")
+    @Parameter(name=ApiConstants.ALLOCATION_STATE, type=CommandType.STRING, description="Change resource state of host, valid values are [Enable, Disable]. Operation may failed if host in states not allowing Enable/Disable")
     private String allocationState;
 
     @Parameter(name=ApiConstants.HOST_TAGS, type=CommandType.LIST, collectionType=CommandType.STRING, description="list of tags to be added to the host")
@@ -103,13 +104,15 @@ public class UpdateHostCmd extends BaseCmd {
 
     @Override
     public void execute(){
-        Host result = _resourceService.updateHost(this);
-        if (result != null) {
+        Host result;
+        try {
+	        result = _resourceService.updateHost(this);
             HostResponse hostResponse = _responseGenerator.createHostResponse(result);
             hostResponse.setResponseName(getCommandName());
             this.setResponseObject(hostResponse);
-        } else {
-            throw new ServerApiException(BaseCmd.INTERNAL_ERROR, "Failed to update host");
-        }   
+        } catch (Exception e) {
+        	s_logger.debug("Failed to update host:" + getId(), e);
+        	throw new ServerApiException(BaseCmd.INTERNAL_ERROR, "Failed to update host:" + getId() + "," + e.getMessage());
+        }
     }
 }
diff --git a/api/src/com/cloud/resource/ResourceService.java b/api/src/com/cloud/resource/ResourceService.java
index 3cd544f4d5d..51ab776b060 100755
--- a/api/src/com/cloud/resource/ResourceService.java
+++ b/api/src/com/cloud/resource/ResourceService.java
@@ -36,6 +36,7 @@ import com.cloud.host.Host;
 import com.cloud.hypervisor.Hypervisor.HypervisorType;
 import com.cloud.org.Cluster;
 import com.cloud.storage.Swift;
+import com.cloud.utils.fsm.NoTransitionException;
 
 public interface ResourceService {
     /**
@@ -44,8 +45,9 @@ public interface ResourceService {
      * @param cmd
      *            - the command specifying hostId
      * @return hostObject
+     * @throws NoTransitionException 
      */
-    Host updateHost(UpdateHostCmd cmd);
+    Host updateHost(UpdateHostCmd cmd) throws NoTransitionException;
 
     Host cancelMaintenance(CancelMaintenanceCmd cmd);
 
diff --git a/api/src/com/cloud/resource/ResourceState.java b/api/src/com/cloud/resource/ResourceState.java
index ecdcfa069c5..71888da8e2b 100755
--- a/api/src/com/cloud/resource/ResourceState.java
+++ b/api/src/com/cloud/resource/ResourceState.java
@@ -3,6 +3,7 @@ package com.cloud.resource;
 import java.util.List;
 import java.util.Set;
 
+import com.cloud.utils.exception.CloudRuntimeException;
 import com.cloud.utils.fsm.StateMachine;
 
 public enum ResourceState {
@@ -40,6 +41,16 @@ public enum ResourceState {
         public String getDescription() {
             return this.comment;
         }
+        
+        public static Event toEvent(String e) {
+        	if (Enable.toString().equals(e)) {
+        		return Enable;
+        	} else if (Disable.toString().equals(e)) {
+        		return Disable;
+        	}
+        	
+        	return null;
+        }
     }
     
     public ResourceState getNextState(Event a) {
diff --git a/server/src/com/cloud/resource/ResourceManagerImpl.java b/server/src/com/cloud/resource/ResourceManagerImpl.java
index acb22213ba1..f4ab83c9b6d 100755
--- a/server/src/com/cloud/resource/ResourceManagerImpl.java
+++ b/server/src/com/cloud/resource/ResourceManagerImpl.java
@@ -1119,18 +1119,26 @@ public class ResourceManagerImpl implements ResourceManager, ResourceService, Ma
     }
 
     @Override
-    public Host updateHost(UpdateHostCmd cmd) {
+    public Host updateHost(UpdateHostCmd cmd) throws NoTransitionException {
         Long hostId = cmd.getId();
         Long guestOSCategoryId = cmd.getOsCategoryId();
 
+        // Verify that the host exists
+        HostVO host = _hostDao.findById(hostId);
+        if (host == null) {
+            throw new InvalidParameterValueException("Host with id " + hostId + " doesn't exist");
+        }
+        
+		if (cmd.getAllocationState() != null) {
+			ResourceState.Event resourceEvent = ResourceState.Event.toEvent(cmd.getAllocationState());
+			if (resourceEvent != ResourceState.Event.Enable && resourceEvent != ResourceState.Event.Disable) {
+				throw new CloudRuntimeException("Invalid allocation state:" + cmd.getAllocationState() + ", only Enable/Disable are allowed");
+			}
+			
+			resourceStateTransitTo(host, resourceEvent, _nodeId);
+		}
+        
         if (guestOSCategoryId != null) {
-
-            // Verify that the host exists
-            HostVO host = _hostDao.findById(hostId);
-            if (host == null) {
-                throw new InvalidParameterValueException("Host with id " + hostId + " doesn't exist");
-            }
-
             // Verify that the guest OS Category exists
             if (guestOSCategoryId > 0) {
                 if (_guestOSCategoryDao.findById(guestOSCategoryId) == null) {
@@ -1150,40 +1158,9 @@ public class ResourceManagerImpl implements ResourceManager, ResourceService, Ma
             }
             _hostDetailsDao.persist(hostId, hostDetails);
         }
-
-        /*
-        String allocationState = cmd.getAllocationState();
-        if (allocationState != null) {
-            // Verify that the host exists
-            HostVO host = _hostDao.findById(hostId);
-            if (host == null) {
-                throw new InvalidParameterValueException("Host with id " + hostId + " doesn't exist");
-            }
-
-            try {
-                HostAllocationState newAllocationState = Host.HostAllocationState.valueOf(allocationState);
-                if (newAllocationState == null) {
-                    s_logger.error("Unable to resolve " + allocationState + " to a valid supported allocation State");
-                    throw new InvalidParameterValueException("Unable to resolve " + allocationState + " to a supported state");
-                } else {
-                    host.setHostAllocationState(newAllocationState);
-                }
-            } catch (IllegalArgumentException ex) {
-                s_logger.error("Unable to resolve " + allocationState + " to a valid supported allocation State");
-                throw new InvalidParameterValueException("Unable to resolve " + allocationState + " to a supported state");
-            }
-
-            _hostDao.update(hostId, host);
-        }
-        */
         
         List<String> hostTags = cmd.getHostTags();
         if (hostTags != null) {
-            // Verify that the host exists
-            HostVO host = _hostDao.findById(hostId);
-            if (host == null) {
-                throw new InvalidParameterValueException("Host with id " + hostId + " doesn't exist");
-            }
             if(s_logger.isDebugEnabled()){
                 s_logger.debug("Updating Host Tags to :"+hostTags);
             }