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Posted to commits@cloudstack.apache.org by bf...@apache.org on 2013/02/13 23:04:21 UTC

[42/50] [abbrv] CLOUDSTACK-684 support vm snapshot

http://git-wip-us.apache.org/repos/asf/incubator-cloudstack/blob/9a12756a/server/src/com/cloud/vm/VirtualMachineManagerImpl.java
----------------------------------------------------------------------
diff --git a/server/src/com/cloud/vm/VirtualMachineManagerImpl.java b/server/src/com/cloud/vm/VirtualMachineManagerImpl.java
index 1838ed2..bb8f8f6 100755
--- a/server/src/com/cloud/vm/VirtualMachineManagerImpl.java
+++ b/server/src/com/cloud/vm/VirtualMachineManagerImpl.java
@@ -158,6 +158,10 @@ import com.cloud.vm.dao.NicDao;
 import com.cloud.vm.dao.SecondaryStorageVmDao;
 import com.cloud.vm.dao.UserVmDao;
 import com.cloud.vm.dao.VMInstanceDao;
+import com.cloud.vm.snapshot.VMSnapshot;
+import com.cloud.vm.snapshot.VMSnapshotManager;
+import com.cloud.vm.snapshot.VMSnapshotVO;
+import com.cloud.vm.snapshot.dao.VMSnapshotDao;
 
 @Local(value = VirtualMachineManager.class)
 public class VirtualMachineManagerImpl extends ManagerBase implements VirtualMachineManager, Listener {
@@ -227,6 +231,8 @@ public class VirtualMachineManagerImpl extends ManagerBase implements VirtualMac
     protected HypervisorGuruManager _hvGuruMgr;
     @Inject
     protected NetworkDao _networkDao;
+    @Inject
+    protected VMSnapshotDao _vmSnapshotDao;
 
     @Inject
     protected List<DeploymentPlanner> _planners;
@@ -236,6 +242,9 @@ public class VirtualMachineManagerImpl extends ManagerBase implements VirtualMac
 
     @Inject
     protected ResourceManager _resourceMgr;
+    
+    @Inject 
+    protected VMSnapshotManager _vmSnapshotMgr = null;
 
     @Inject
     protected ConfigurationDao _configDao;
@@ -590,7 +599,7 @@ public class VirtualMachineManagerImpl extends ManagerBase implements VirtualMac
     ConcurrentOperationException, ResourceUnavailableException {
         return advanceStart(vm, params, caller, account, null);
     }
-
+    
     @Override
     public <T extends VMInstanceVO> T advanceStart(T vm, Map<VirtualMachineProfile.Param, Object> params, User caller, Account account, DeploymentPlan planToDeploy)
             throws InsufficientCapacityException, ConcurrentOperationException, ResourceUnavailableException {
@@ -1143,6 +1152,12 @@ public class VirtualMachineManagerImpl extends ManagerBase implements VirtualMac
 
     @Override
     public boolean stateTransitTo(VMInstanceVO vm, VirtualMachine.Event e, Long hostId) throws NoTransitionException {
+        // if there are active vm snapshots task, state change is not allowed
+        if(_vmSnapshotMgr.hasActiveVMSnapshotTasks(vm.getId())){
+            s_logger.error("State transit with event: " + e + " failed due to: " + vm.getInstanceName() + " has active VM snapshots tasks");
+            return false;
+        }
+        
         State oldState = vm.getState();
         if (oldState == State.Starting) {
             if (e == Event.OperationSucceeded) {
@@ -1177,7 +1192,12 @@ public class VirtualMachineManagerImpl extends ManagerBase implements VirtualMac
             s_logger.debug("Unable to stop " + vm);
             return false;
         }
-
+        
+        if (!_vmSnapshotMgr.deleteAllVMSnapshots(vm.getId(),null)){
+            s_logger.debug("Unable to delete all snapshots for " + vm);
+            return false;
+        }
+        
         try {
             if (!stateTransitTo(vm, VirtualMachine.Event.DestroyRequested, vm.getHostId())) {
                 s_logger.debug("Unable to destroy the vm because it is not in the correct state: " + vm);
@@ -1626,6 +1646,19 @@ public class VirtualMachineManagerImpl extends ManagerBase implements VirtualMac
         s_logger.debug("Found " + vms.size() + " VMs for host " + hostId);
         for (VMInstanceVO vm : vms) {
             AgentVmInfo info = infos.remove(vm.getId());
+            
+            // sync VM Snapshots related transient states
+            List<VMSnapshotVO> vmSnapshotsInTrasientStates = _vmSnapshotDao.listByInstanceId(vm.getId(), VMSnapshot.State.Expunging,VMSnapshot.State.Reverting, VMSnapshot.State.Creating);
+            if(vmSnapshotsInTrasientStates.size() > 1){
+                s_logger.info("Found vm " + vm.getInstanceName() + " with VM snapshots in transient states, needs to sync VM snapshot state");
+                if(!_vmSnapshotMgr.syncVMSnapshot(vm, hostId)){
+                    s_logger.warn("Failed to sync VM in a transient snapshot related state: " + vm.getInstanceName());
+                    continue;
+                }else{
+                    s_logger.info("Successfully sync VM with transient snapshot: " + vm.getInstanceName());
+                }
+            }
+            
             VMInstanceVO castedVm = null;
             if (info == null) {
                 info = new AgentVmInfo(vm.getInstanceName(), getVmGuru(vm), vm, State.Stopped);
@@ -1743,8 +1776,27 @@ public class VirtualMachineManagerImpl extends ManagerBase implements VirtualMac
         for (VMInstanceVO vm : set_vms) {
             AgentVmInfo info =  infos.remove(vm.getId());
             VMInstanceVO castedVm = null;
-            if ((info == null && (vm.getState() == State.Running || vm.getState() == State.Starting))  
-                    ||  (info != null && (info.state == State.Running && vm.getState() == State.Starting))) 
+            
+            // sync VM Snapshots related transient states
+            List<VMSnapshotVO> vmSnapshotsInExpungingStates = _vmSnapshotDao.listByInstanceId(vm.getId(), VMSnapshot.State.Expunging, VMSnapshot.State.Creating,VMSnapshot.State.Reverting);
+            if(vmSnapshotsInExpungingStates.size() > 0){
+                s_logger.info("Found vm " + vm.getInstanceName() + " in state. " + vm.getState() + ", needs to sync VM snapshot state");
+                Long hostId = null;
+                Host host = null;
+                if(info != null && info.getHostUuid() != null){
+                    host = _hostDao.findByGuid(info.getHostUuid());
+                }
+                hostId = host == null ? (vm.getHostId() == null ? vm.getLastHostId() : vm.getHostId()) : host.getId();
+                if(!_vmSnapshotMgr.syncVMSnapshot(vm, hostId)){
+                    s_logger.warn("Failed to sync VM with transient snapshot: " + vm.getInstanceName());
+                    continue;
+                }else{
+                    s_logger.info("Successfully sync VM with transient snapshot: " + vm.getInstanceName());
+                }
+            }
+            
+            if ((info == null && (vm.getState() == State.Running || vm.getState() == State.Starting ))  
+            		||  (info != null && (info.state == State.Running && vm.getState() == State.Starting))) 
             {
                 s_logger.info("Found vm " + vm.getInstanceName() + " in inconsistent state. " + vm.getState() + " on CS while " +  (info == null ? "Stopped" : "Running") + " on agent");
                 info = new AgentVmInfo(vm.getInstanceName(), getVmGuru(vm), vm, State.Stopped);
@@ -1785,7 +1837,7 @@ public class VirtualMachineManagerImpl extends ManagerBase implements VirtualMac
                 }
             }
             else if (info != null && (vm.getState() == State.Stopped || vm.getState() == State.Stopping
-                    || vm.isRemoved() || vm.getState() == State.Destroyed || vm.getState() == State.Expunging)) {
+                    || vm.isRemoved() || vm.getState() == State.Destroyed || vm.getState() == State.Expunging )) {
                 Host host = _hostDao.findByGuid(info.getHostUuid());
                 if (host != null){
                     s_logger.warn("Stopping a VM which is stopped/stopping/destroyed/expunging " + info.name);
@@ -2260,6 +2312,7 @@ public class VirtualMachineManagerImpl extends ManagerBase implements VirtualMac
 
         Long clusterId = agent.getClusterId();
         long agentId = agent.getId();
+
         if (agent.getHypervisorType() == HypervisorType.XenServer) { // only for Xen
             StartupRoutingCommand startup = (StartupRoutingCommand) cmd;
             HashMap<String, Pair<String, State>> allStates = startup.getClusterVMStateChanges();
@@ -2375,7 +2428,7 @@ public class VirtualMachineManagerImpl extends ManagerBase implements VirtualMac
         if (newServiceOffering == null) {
             throw new InvalidParameterValueException("Unable to find a service offering with id " + newServiceOfferingId);
         }
-
+		
         // Check that the VM is stopped
         if (!vmInstance.getState().equals(State.Stopped)) {
             s_logger.warn("Unable to upgrade virtual machine " + vmInstance.toString() + " in state " + vmInstance.getState());

http://git-wip-us.apache.org/repos/asf/incubator-cloudstack/blob/9a12756a/server/src/com/cloud/vm/snapshot/VMSnapshotManager.java
----------------------------------------------------------------------
diff --git a/server/src/com/cloud/vm/snapshot/VMSnapshotManager.java b/server/src/com/cloud/vm/snapshot/VMSnapshotManager.java
new file mode 100644
index 0000000..c609005
--- /dev/null
+++ b/server/src/com/cloud/vm/snapshot/VMSnapshotManager.java
@@ -0,0 +1,47 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package com.cloud.vm.snapshot;
+
+import com.cloud.utils.component.Manager;
+import com.cloud.vm.VMInstanceVO;
+
+public interface VMSnapshotManager extends VMSnapshotService, Manager {
+    public static final int VMSNAPSHOTMAX = 10;
+
+    
+    /**
+     * Delete all VM snapshots belonging to one VM
+     * @param id, VM id
+     * @param type, 
+     * @return true for success, false for failure
+     */
+    boolean deleteAllVMSnapshots(long id, VMSnapshot.Type type);
+
+    /**
+     * Sync VM snapshot state when VM snapshot in reverting or snapshoting or expunging state
+     * Used for fullsync after agent connects
+     * 
+     * @param vm, the VM in question
+     * @param hostId
+     * @return true if succeeds, false if fails
+     */
+    boolean syncVMSnapshot(VMInstanceVO vm, Long hostId);
+
+    boolean hasActiveVMSnapshotTasks(Long vmId);
+
+}

http://git-wip-us.apache.org/repos/asf/incubator-cloudstack/blob/9a12756a/server/src/com/cloud/vm/snapshot/VMSnapshotManagerImpl.java
----------------------------------------------------------------------
diff --git a/server/src/com/cloud/vm/snapshot/VMSnapshotManagerImpl.java b/server/src/com/cloud/vm/snapshot/VMSnapshotManagerImpl.java
new file mode 100644
index 0000000..a033563
--- /dev/null
+++ b/server/src/com/cloud/vm/snapshot/VMSnapshotManagerImpl.java
@@ -0,0 +1,833 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package com.cloud.vm.snapshot;
+
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import javax.ejb.Local;
+import javax.inject.Inject;
+import javax.naming.ConfigurationException;
+
+import org.apache.cloudstack.api.command.user.vmsnapshot.ListVMSnapshotCmd;
+import org.apache.log4j.Logger;
+import org.springframework.stereotype.Component;
+
+import com.cloud.agent.AgentManager;
+import com.cloud.agent.api.Answer;
+import com.cloud.agent.api.Command;
+import com.cloud.agent.api.CreateVMSnapshotAnswer;
+import com.cloud.agent.api.CreateVMSnapshotCommand;
+import com.cloud.agent.api.DeleteVMSnapshotAnswer;
+import com.cloud.agent.api.DeleteVMSnapshotCommand;
+import com.cloud.agent.api.RevertToVMSnapshotAnswer;
+import com.cloud.agent.api.RevertToVMSnapshotCommand;
+import com.cloud.agent.api.VMSnapshotTO;
+import com.cloud.agent.api.to.VolumeTO;
+import com.cloud.configuration.dao.ConfigurationDao;
+import com.cloud.event.ActionEvent;
+import com.cloud.event.EventTypes;
+import com.cloud.exception.AgentUnavailableException;
+import com.cloud.exception.ConcurrentOperationException;
+import com.cloud.exception.InsufficientCapacityException;
+import com.cloud.exception.InvalidParameterValueException;
+import com.cloud.exception.OperationTimedoutException;
+import com.cloud.exception.ResourceAllocationException;
+import com.cloud.exception.ResourceUnavailableException;
+import com.cloud.host.Host;
+import com.cloud.host.HostVO;
+import com.cloud.host.dao.HostDao;
+import com.cloud.hypervisor.Hypervisor.HypervisorType;
+import com.cloud.hypervisor.HypervisorGuruManager;
+import com.cloud.projects.Project.ListProjectResourcesCriteria;
+import com.cloud.storage.GuestOSVO;
+import com.cloud.storage.Snapshot;
+import com.cloud.storage.SnapshotVO;
+import com.cloud.storage.StoragePoolVO;
+import com.cloud.storage.VolumeVO;
+import com.cloud.storage.dao.GuestOSDao;
+import com.cloud.storage.dao.SnapshotDao;
+import com.cloud.storage.dao.StoragePoolDao;
+import com.cloud.storage.dao.VolumeDao;
+import com.cloud.user.Account;
+import com.cloud.user.AccountManager;
+import com.cloud.user.UserContext;
+import com.cloud.user.UserVO;
+import com.cloud.user.dao.AccountDao;
+import com.cloud.user.dao.UserDao;
+import com.cloud.uservm.UserVm;
+import com.cloud.utils.DateUtil;
+import com.cloud.utils.NumbersUtil;
+import com.cloud.utils.Ternary;
+import com.cloud.utils.component.ManagerBase;
+import com.cloud.utils.db.DB;
+import com.cloud.utils.db.Filter;
+import com.cloud.utils.db.SearchBuilder;
+import com.cloud.utils.db.SearchCriteria;
+import com.cloud.utils.db.Transaction;
+import com.cloud.utils.exception.CloudRuntimeException;
+import com.cloud.utils.fsm.NoTransitionException;
+import com.cloud.utils.fsm.StateMachine2;
+import com.cloud.vm.UserVmVO;
+import com.cloud.vm.VMInstanceVO;
+import com.cloud.vm.VirtualMachine;
+import com.cloud.vm.VirtualMachine.State;
+import com.cloud.vm.VirtualMachineManager;
+import com.cloud.vm.VirtualMachineProfile;
+import com.cloud.vm.dao.UserVmDao;
+import com.cloud.vm.dao.VMInstanceDao;
+import com.cloud.vm.snapshot.dao.VMSnapshotDao;
+
+@Component
+@Local(value = { VMSnapshotManager.class, VMSnapshotService.class })
+public class VMSnapshotManagerImpl extends ManagerBase implements VMSnapshotManager, VMSnapshotService {
+    private static final Logger s_logger = Logger.getLogger(VMSnapshotManagerImpl.class);
+    String _name;
+    @Inject VMSnapshotDao _vmSnapshotDao;
+    @Inject VolumeDao _volumeDao;
+    @Inject AccountDao _accountDao;
+    @Inject VMInstanceDao _vmInstanceDao;
+    @Inject UserVmDao _userVMDao;
+    @Inject HostDao _hostDao;
+    @Inject UserDao _userDao;
+    @Inject AgentManager _agentMgr;
+    @Inject HypervisorGuruManager _hvGuruMgr;
+    @Inject AccountManager _accountMgr;
+    @Inject GuestOSDao _guestOSDao;
+    @Inject StoragePoolDao _storagePoolDao;
+    @Inject SnapshotDao _snapshotDao;
+    @Inject VirtualMachineManager _itMgr;
+    @Inject ConfigurationDao _configDao;
+    int _vmSnapshotMax;
+    StateMachine2<VMSnapshot.State, VMSnapshot.Event, VMSnapshot> _vmSnapshottateMachine ;
+
+    @Override
+    public boolean configure(String name, Map<String, Object> params) throws ConfigurationException {
+        _name = name;
+        if (_configDao == null) {
+            throw new ConfigurationException(
+                    "Unable to get the configuration dao.");
+        }
+
+        _vmSnapshotMax = NumbersUtil.parseInt(_configDao.getValue("vmsnapshot.max"), VMSNAPSHOTMAX);
+
+        _vmSnapshottateMachine   = VMSnapshot.State.getStateMachine();
+        return true;
+    }
+
+    @Override
+    public boolean start() {
+        return true;
+    }
+
+    @Override
+    public boolean stop() {
+        return true;
+    }
+
+    @Override
+    public List<VMSnapshotVO> listVMSnapshots(ListVMSnapshotCmd cmd) {
+        Account caller = getCaller();
+        List<Long> permittedAccounts = new ArrayList<Long>();
+
+        boolean listAll = cmd.listAll();
+        Long id = cmd.getId();
+        Long vmId = cmd.getVmId();
+        
+        String state = cmd.getState();
+        String keyword = cmd.getKeyword();
+        String name = cmd.getVmSnapshotName();
+        String accountName = cmd.getAccountName();
+
+        Ternary<Long, Boolean, ListProjectResourcesCriteria> domainIdRecursiveListProject = new Ternary<Long, Boolean, ListProjectResourcesCriteria>(
+                cmd.getDomainId(), cmd.isRecursive(), null);
+        _accountMgr.buildACLSearchParameters(caller, id, cmd.getAccountName(), cmd.getProjectId(), permittedAccounts, domainIdRecursiveListProject, listAll,
+                false);
+        Long domainId = domainIdRecursiveListProject.first();
+        Boolean isRecursive = domainIdRecursiveListProject.second();
+        ListProjectResourcesCriteria listProjectResourcesCriteria = domainIdRecursiveListProject.third();
+
+        Filter searchFilter = new Filter(VMSnapshotVO.class, "created", false, cmd.getStartIndex(), cmd.getPageSizeVal());
+        SearchBuilder<VMSnapshotVO> sb = _vmSnapshotDao.createSearchBuilder();
+        _accountMgr.buildACLSearchBuilder(sb, domainId, isRecursive, permittedAccounts, listProjectResourcesCriteria);
+
+        sb.and("vm_id", sb.entity().getVmId(), SearchCriteria.Op.EQ);
+        sb.and("domain_id", sb.entity().getDomainId(), SearchCriteria.Op.EQ);
+        sb.and("status", sb.entity().getState(), SearchCriteria.Op.IN);
+        sb.and("state", sb.entity().getState(), SearchCriteria.Op.EQ);
+        sb.and("id", sb.entity().getId(), SearchCriteria.Op.EQ);
+        sb.and("display_name", sb.entity().getDisplayName(), SearchCriteria.Op.EQ);
+        sb.and("account_id", sb.entity().getAccountId(), SearchCriteria.Op.EQ);
+        sb.done();
+
+        SearchCriteria<VMSnapshotVO> sc = sb.create();
+        _accountMgr.buildACLSearchCriteria(sc, domainId, isRecursive, permittedAccounts, listProjectResourcesCriteria);
+
+        if (accountName != null && cmd.getDomainId() != null) {
+            Account account = _accountMgr.getActiveAccountByName(accountName, cmd.getDomainId());
+            sc.setParameters("account_id", account.getId());
+        }
+
+        if (vmId != null) {
+            sc.setParameters("vm_id", vmId);
+        }
+
+        if (domainId != null) {
+            sc.setParameters("domain_id", domainId);
+        }
+
+        if (state == null) {
+            VMSnapshot.State[] status = { VMSnapshot.State.Ready, VMSnapshot.State.Creating, VMSnapshot.State.Allocated, 
+                    VMSnapshot.State.Error, VMSnapshot.State.Expunging, VMSnapshot.State.Reverting };
+            sc.setParameters("status", (Object[]) status);
+        } else {
+            sc.setParameters("state", state);
+        }
+
+        if (name != null) {
+            sc.setParameters("display_name", name);
+        }
+
+        if (keyword != null) {
+            SearchCriteria<VMSnapshotVO> ssc = _vmSnapshotDao.createSearchCriteria();
+            ssc.addOr("name", SearchCriteria.Op.LIKE, "%" + keyword + "%");
+            ssc.addOr("display_name", SearchCriteria.Op.LIKE, "%" + keyword + "%");
+            ssc.addOr("description", SearchCriteria.Op.LIKE, "%" + keyword + "%");
+            sc.addAnd("name", SearchCriteria.Op.SC, ssc);
+        }
+
+        if (id != null) {
+            sc.setParameters("id", id);
+        }
+
+        return _vmSnapshotDao.search(sc, searchFilter);
+    
+    }
+
+    protected Account getCaller(){
+        return UserContext.current().getCaller();
+    }
+    
+    @Override
+    public VMSnapshot allocVMSnapshot(Long vmId, String vsDisplayName, String vsDescription, Boolean snapshotMemory) 
+            throws ResourceAllocationException {
+
+        Account caller = getCaller();
+
+        // check if VM exists
+        UserVmVO userVmVo = _userVMDao.findById(vmId);
+        if (userVmVo == null) {
+            throw new InvalidParameterValueException("Creating VM snapshot failed due to VM:" + vmId + " is a system VM or does not exist");
+        }
+        
+        // parameter length check
+        if(vsDisplayName != null && vsDisplayName.length()>255)
+            throw new InvalidParameterValueException("Creating VM snapshot failed due to length of VM snapshot vsDisplayName should not exceed 255");
+        if(vsDescription != null && vsDescription.length()>255)
+            throw new InvalidParameterValueException("Creating VM snapshot failed due to length of VM snapshot vsDescription should not exceed 255");
+        
+        // VM snapshot display name must be unique for a VM
+        String timeString = DateUtil.getDateDisplayString(DateUtil.GMT_TIMEZONE, new Date(), DateUtil.YYYYMMDD_FORMAT);
+        String vmSnapshotName = userVmVo.getInstanceName() + "_VS_" + timeString;
+        if (vsDisplayName == null) {
+            vsDisplayName = vmSnapshotName;
+        }
+        if(_vmSnapshotDao.findByName(vmId,vsDisplayName) != null){
+            throw new InvalidParameterValueException("Creating VM snapshot failed due to VM snapshot with name" + vsDisplayName + "  already exists"); 
+        }
+        
+        // check VM state
+        if (userVmVo.getState() != VirtualMachine.State.Running && userVmVo.getState() != VirtualMachine.State.Stopped) {
+            throw new InvalidParameterValueException("Creating vm snapshot failed due to VM:" + vmId + " is not in the running or Stopped state");
+        }
+        
+        if(snapshotMemory && userVmVo.getState() == VirtualMachine.State.Stopped){
+            throw new InvalidParameterValueException("Can not snapshot memory when VM is in stopped state");
+        }
+        
+        // for KVM, only allow snapshot with memory when VM is in running state
+        if(userVmVo.getHypervisorType() == HypervisorType.KVM && userVmVo.getState() == State.Running && !snapshotMemory){
+            throw new InvalidParameterValueException("KVM VM does not allow to take a disk-only snapshot when VM is in running state");
+        }
+        
+        // check access
+        _accountMgr.checkAccess(caller, null, true, userVmVo);
+
+        // check max snapshot limit for per VM
+        if (_vmSnapshotDao.findByVm(vmId).size() >= _vmSnapshotMax) {
+            throw new CloudRuntimeException("Creating vm snapshot failed due to a VM can just have : " + _vmSnapshotMax
+                    + " VM snapshots. Please delete old ones");
+        }
+
+        // check if there are active volume snapshots tasks
+        List<VolumeVO> listVolumes = _volumeDao.findByInstance(vmId);
+        for (VolumeVO volume : listVolumes) {
+            List<SnapshotVO> activeSnapshots = _snapshotDao.listByInstanceId(volume.getInstanceId(), Snapshot.State.Creating,
+                    Snapshot.State.CreatedOnPrimary, Snapshot.State.BackingUp);
+            if (activeSnapshots.size() > 0) {
+                throw new CloudRuntimeException(
+                        "There is other active volume snapshot tasks on the instance to which the volume is attached, please try again later.");
+            }
+        }
+        
+        // check if there are other active VM snapshot tasks
+        if (hasActiveVMSnapshotTasks(vmId)) {
+            throw new CloudRuntimeException("There is other active vm snapshot tasks on the instance, please try again later");
+        }
+        
+        VMSnapshot.Type vmSnapshotType = VMSnapshot.Type.Disk;
+        if(snapshotMemory && userVmVo.getState() == VirtualMachine.State.Running)
+            vmSnapshotType = VMSnapshot.Type.DiskAndMemory;
+        
+        try {
+            VMSnapshotVO vmSnapshotVo = new VMSnapshotVO(userVmVo.getAccountId(), userVmVo.getDomainId(), vmId, vsDescription, vmSnapshotName,
+                    vsDisplayName, userVmVo.getServiceOfferingId(), vmSnapshotType, null);
+            VMSnapshot vmSnapshot = _vmSnapshotDao.persist(vmSnapshotVo);
+            if (vmSnapshot == null) {
+                throw new CloudRuntimeException("Failed to create snapshot for vm: " + vmId);
+            }
+            return vmSnapshot;
+        } catch (Exception e) {
+            String msg = e.getMessage();
+            s_logger.error("Create vm snapshot record failed for vm: " + vmId + " due to: " + msg);
+        }  
+        return null;
+    }
+
+    @Override
+    public String getName() {
+        return _name;
+    }
+
+    @Override
+    @ActionEvent(eventType = EventTypes.EVENT_VM_SNAPSHOT_CREATE, eventDescription = "creating VM snapshot", async = true)
+    public VMSnapshot creatVMSnapshot(Long vmId, Long vmSnapshotId) {
+        UserVmVO userVm = _userVMDao.findById(vmId);
+        if (userVm == null) {
+            throw new InvalidParameterValueException("Create vm to snapshot failed due to vm: " + vmId + " is not found");
+        }
+        VMSnapshotVO vmSnapshot = _vmSnapshotDao.findById(vmSnapshotId);
+        if(vmSnapshot == null){
+            throw new CloudRuntimeException("VM snapshot id: " + vmSnapshotId + " can not be found");
+        }
+        Long hostId = pickRunningHost(vmId);
+        try {
+            vmSnapshotStateTransitTo(vmSnapshot, VMSnapshot.Event.CreateRequested);
+        } catch (NoTransitionException e) {
+            throw new CloudRuntimeException(e.getMessage());
+        }
+        return createVmSnapshotInternal(userVm, vmSnapshot, hostId);
+    }
+
+    protected VMSnapshot createVmSnapshotInternal(UserVmVO userVm, VMSnapshotVO vmSnapshot, Long hostId) {
+        try { 
+            CreateVMSnapshotAnswer answer = null;
+            GuestOSVO guestOS = _guestOSDao.findById(userVm.getGuestOSId());
+            
+            // prepare snapshotVolumeTos
+            List<VolumeTO> volumeTOs = getVolumeTOList(userVm.getId());
+            
+            // prepare target snapshotTO and its parent snapshot (current snapshot)
+            VMSnapshotTO current = null;
+            VMSnapshotVO currentSnapshot = _vmSnapshotDao.findCurrentSnapshotByVmId(userVm.getId());
+            if (currentSnapshot != null)
+                current = getSnapshotWithParents(currentSnapshot);
+            VMSnapshotTO target = new VMSnapshotTO(vmSnapshot.getId(),  vmSnapshot.getName(), vmSnapshot.getType(), null, vmSnapshot.getDescription(), false,
+                    current);
+            if (current == null)
+                vmSnapshot.setParent(null);
+            else
+                vmSnapshot.setParent(current.getId());
+
+            CreateVMSnapshotCommand ccmd = new CreateVMSnapshotCommand(userVm.getInstanceName(),target ,volumeTOs, guestOS.getDisplayName(),userVm.getState());
+            
+            answer = (CreateVMSnapshotAnswer) sendToPool(hostId, ccmd);
+            if (answer != null && answer.getResult()) {
+                processAnswer(vmSnapshot, userVm, answer, hostId);
+                s_logger.debug("Create vm snapshot " + vmSnapshot.getName() + " succeeded for vm: " + userVm.getInstanceName());
+            }else{
+                String errMsg = answer.getDetails();
+                s_logger.error("Agent reports creating vm snapshot " + vmSnapshot.getName() + " failed for vm: " + userVm.getInstanceName() + " due to " + errMsg);
+                vmSnapshotStateTransitTo(vmSnapshot, VMSnapshot.Event.OperationFailed);
+            }
+            return vmSnapshot;
+        } catch (Exception e) {
+            if(e instanceof AgentUnavailableException){
+                try {
+                    vmSnapshotStateTransitTo(vmSnapshot, VMSnapshot.Event.OperationFailed);
+                } catch (NoTransitionException e1) {
+                    s_logger.error("Cannot set vm snapshot state due to: " + e1.getMessage());
+                }
+            }
+            String msg = e.getMessage();
+            s_logger.error("Create vm snapshot " + vmSnapshot.getName() + " failed for vm: " + userVm.getInstanceName() + " due to " + msg);
+            throw new CloudRuntimeException(msg);
+        } finally{
+            if(vmSnapshot.getState() == VMSnapshot.State.Allocated){
+                s_logger.warn("Create vm snapshot " + vmSnapshot.getName() + " failed for vm: " + userVm.getInstanceName());
+                _vmSnapshotDao.remove(vmSnapshot.getId());
+            }
+        }
+    }
+
+    protected List<VolumeTO> getVolumeTOList(Long vmId) {
+        List<VolumeTO> volumeTOs = new ArrayList<VolumeTO>();
+        List<VolumeVO> volumeVos = _volumeDao.findByInstance(vmId);
+        
+        for (VolumeVO volume : volumeVos) {
+            StoragePoolVO pool = _storagePoolDao.findById(volume.getPoolId());
+            VolumeTO volumeTO = new VolumeTO(volume, pool);
+            volumeTOs.add(volumeTO);
+        }
+        return volumeTOs;
+    }
+
+    // get snapshot and its parents recursively
+    private VMSnapshotTO getSnapshotWithParents(VMSnapshotVO snapshot) {
+        Map<Long, VMSnapshotVO> snapshotMap = new HashMap<Long, VMSnapshotVO>();
+        List<VMSnapshotVO> allSnapshots = _vmSnapshotDao.findByVm(snapshot.getVmId());
+        for (VMSnapshotVO vmSnapshotVO : allSnapshots) {
+            snapshotMap.put(vmSnapshotVO.getId(), vmSnapshotVO);
+        }
+
+        VMSnapshotTO currentTO = convert2VMSnapshotTO(snapshot);
+        VMSnapshotTO result = currentTO;
+        VMSnapshotVO current = snapshot;
+        while (current.getParent() != null) {
+            VMSnapshotVO parent = snapshotMap.get(current.getParent());
+            currentTO.setParent(convert2VMSnapshotTO(parent));
+            current = snapshotMap.get(current.getParent());
+            currentTO = currentTO.getParent();
+        }
+        return result;
+    }
+
+    private VMSnapshotTO convert2VMSnapshotTO(VMSnapshotVO vo) {
+        return new VMSnapshotTO(vo.getId(), vo.getName(),  vo.getType(), vo.getCreated().getTime(), vo.getDescription(),
+                vo.getCurrent(), null);
+    }
+
+    protected boolean vmSnapshotStateTransitTo(VMSnapshotVO vsnp, VMSnapshot.Event event) throws NoTransitionException {
+        return _vmSnapshottateMachine.transitTo(vsnp, event, null, _vmSnapshotDao);
+    }
+    
+    @DB
+    protected void processAnswer(VMSnapshotVO vmSnapshot, UserVmVO  userVm, Answer as, Long hostId) {
+        final Transaction txn = Transaction.currentTxn();
+        try {
+            txn.start();
+            if (as instanceof CreateVMSnapshotAnswer) {
+                CreateVMSnapshotAnswer answer = (CreateVMSnapshotAnswer) as;
+                finalizeCreate(vmSnapshot, answer.getVolumeTOs());
+                vmSnapshotStateTransitTo(vmSnapshot, VMSnapshot.Event.OperationSucceeded);
+            } else if (as instanceof RevertToVMSnapshotAnswer) {
+                RevertToVMSnapshotAnswer answer = (RevertToVMSnapshotAnswer) as;
+                finalizeRevert(vmSnapshot, answer.getVolumeTOs());
+                vmSnapshotStateTransitTo(vmSnapshot, VMSnapshot.Event.OperationSucceeded);
+            } else if (as instanceof DeleteVMSnapshotAnswer) {
+                DeleteVMSnapshotAnswer answer = (DeleteVMSnapshotAnswer) as;
+                finalizeDelete(vmSnapshot, answer.getVolumeTOs());
+                _vmSnapshotDao.remove(vmSnapshot.getId());
+            }
+            txn.commit();
+        } catch (Exception e) {
+            String errMsg = "Error while process answer: " + as.getClass() + " due to " + e.getMessage();
+            s_logger.error(errMsg, e);
+            txn.rollback();
+            throw new CloudRuntimeException(errMsg);
+        } finally {
+            txn.close();
+        }
+    }
+
+    protected void finalizeDelete(VMSnapshotVO vmSnapshot, List<VolumeTO> VolumeTOs) {
+        // update volumes path
+        updateVolumePath(VolumeTOs);
+        
+        // update children's parent snapshots
+        List<VMSnapshotVO> children= _vmSnapshotDao.listByParent(vmSnapshot.getId());
+        for (VMSnapshotVO child : children) {
+            child.setParent(vmSnapshot.getParent());
+            _vmSnapshotDao.persist(child);
+        }
+        
+        // update current snapshot 
+        VMSnapshotVO current = _vmSnapshotDao.findCurrentSnapshotByVmId(vmSnapshot.getVmId());
+        if(current != null && current.getId() == vmSnapshot.getId() && vmSnapshot.getParent() != null){
+            VMSnapshotVO parent = _vmSnapshotDao.findById(vmSnapshot.getParent());
+            parent.setCurrent(true);
+            _vmSnapshotDao.persist(parent);
+        }
+        vmSnapshot.setCurrent(false);
+        _vmSnapshotDao.persist(vmSnapshot);
+    }
+
+    protected void finalizeCreate(VMSnapshotVO vmSnapshot, List<VolumeTO> VolumeTOs) {
+        // update volumes path
+        updateVolumePath(VolumeTOs);
+        
+        vmSnapshot.setCurrent(true);
+        
+        // change current snapshot
+        if (vmSnapshot.getParent() != null) {
+            VMSnapshotVO previousCurrent = _vmSnapshotDao.findById(vmSnapshot.getParent());
+            previousCurrent.setCurrent(false);
+            _vmSnapshotDao.persist(previousCurrent);
+        }
+        _vmSnapshotDao.persist(vmSnapshot);
+    }
+
+    protected void finalizeRevert(VMSnapshotVO vmSnapshot, List<VolumeTO> volumeToList) {
+        // update volumes path
+        updateVolumePath(volumeToList);
+
+        // update current snapshot, current snapshot is the one reverted to
+        VMSnapshotVO previousCurrent = _vmSnapshotDao.findCurrentSnapshotByVmId(vmSnapshot.getVmId());
+        if(previousCurrent != null){
+            previousCurrent.setCurrent(false);
+            _vmSnapshotDao.persist(previousCurrent);
+        }
+        vmSnapshot.setCurrent(true);
+        _vmSnapshotDao.persist(vmSnapshot);
+    }
+
+    private void updateVolumePath(List<VolumeTO> volumeTOs) {
+        for (VolumeTO volume : volumeTOs) {
+            if (volume.getPath() != null) {
+                VolumeVO volumeVO = _volumeDao.findById(volume.getId());
+                volumeVO.setPath(volume.getPath());
+                _volumeDao.persist(volumeVO);
+            }
+        }
+    }
+    
+    public VMSnapshotManagerImpl() {
+        
+    }
+    
+    protected Answer sendToPool(Long hostId, Command cmd) throws AgentUnavailableException, OperationTimedoutException {
+        long targetHostId = _hvGuruMgr.getGuruProcessedCommandTargetHost(hostId, cmd);
+        Answer answer = _agentMgr.send(targetHostId, cmd);
+        return answer;
+    }
+    
+    @Override
+    public boolean hasActiveVMSnapshotTasks(Long vmId){
+        List<VMSnapshotVO> activeVMSnapshots = _vmSnapshotDao.listByInstanceId(vmId, 
+                VMSnapshot.State.Creating, VMSnapshot.State.Expunging,VMSnapshot.State.Reverting,VMSnapshot.State.Allocated);
+        return activeVMSnapshots.size() > 0;
+    }
+
+    @Override
+    @ActionEvent(eventType = EventTypes.EVENT_VM_SNAPSHOT_DELETE, eventDescription = "delete vm snapshots", async=true)
+    public boolean deleteVMSnapshot(Long vmSnapshotId) {
+        Account caller = getCaller();
+
+        VMSnapshotVO vmSnapshot = _vmSnapshotDao.findById(vmSnapshotId);
+        if (vmSnapshot == null) {
+            throw new InvalidParameterValueException("unable to find the vm snapshot with id " + vmSnapshotId);
+        }
+
+        _accountMgr.checkAccess(caller, null, true, vmSnapshot);
+        
+        // check VM snapshot states, only allow to delete vm snapshots in created and error state
+        if (VMSnapshot.State.Ready != vmSnapshot.getState() && VMSnapshot.State.Expunging != vmSnapshot.getState() && VMSnapshot.State.Error != vmSnapshot.getState()) {
+            throw new InvalidParameterValueException("Can't delete the vm snapshotshot " + vmSnapshotId + " due to it is not in Created or Error, or Expunging State");
+        }
+        
+        // check if there are other active VM snapshot tasks
+        if (hasActiveVMSnapshotTasks(vmSnapshot.getVmId())) {
+            List<VMSnapshotVO> expungingSnapshots = _vmSnapshotDao.listByInstanceId(vmSnapshot.getVmId(), VMSnapshot.State.Expunging);
+            if(expungingSnapshots.size() > 0 && expungingSnapshots.get(0).getId() == vmSnapshot.getId())
+                s_logger.debug("Target VM snapshot already in expunging state, go on deleting it: " + vmSnapshot.getDisplayName());
+            else
+                throw new InvalidParameterValueException("There is other active vm snapshot tasks on the instance, please try again later");
+        }
+
+        if(vmSnapshot.getState() == VMSnapshot.State.Allocated){
+            return _vmSnapshotDao.remove(vmSnapshot.getId());
+        }else{
+            return deleteSnapshotInternal(vmSnapshot);
+        }
+    }
+
+    @DB
+    protected boolean deleteSnapshotInternal(VMSnapshotVO vmSnapshot) {
+        UserVmVO userVm = _userVMDao.findById(vmSnapshot.getVmId());
+        
+        try {
+            vmSnapshotStateTransitTo(vmSnapshot,VMSnapshot.Event.ExpungeRequested);
+            Long hostId = pickRunningHost(vmSnapshot.getVmId());
+
+            // prepare snapshotVolumeTos
+            List<VolumeTO> volumeTOs = getVolumeTOList(vmSnapshot.getVmId());
+            
+            // prepare DeleteVMSnapshotCommand
+            String vmInstanceName = userVm.getInstanceName();
+            VMSnapshotTO parent = getSnapshotWithParents(vmSnapshot).getParent();
+            VMSnapshotTO vmSnapshotTO = new VMSnapshotTO(vmSnapshot.getId(), vmSnapshot.getName(), vmSnapshot.getType(), 
+                    vmSnapshot.getCreated().getTime(), vmSnapshot.getDescription(), vmSnapshot.getCurrent(), parent);
+            GuestOSVO guestOS = _guestOSDao.findById(userVm.getGuestOSId());
+            DeleteVMSnapshotCommand deleteSnapshotCommand = new DeleteVMSnapshotCommand(vmInstanceName, vmSnapshotTO, volumeTOs,guestOS.getDisplayName());
+            
+            DeleteVMSnapshotAnswer answer = (DeleteVMSnapshotAnswer) sendToPool(hostId, deleteSnapshotCommand);
+           
+            if (answer != null && answer.getResult()) {
+                processAnswer(vmSnapshot, userVm, answer, hostId);
+                s_logger.debug("Delete VM snapshot " + vmSnapshot.getName() + " succeeded for vm: " + userVm.getInstanceName());
+                return true;
+            } else {
+                s_logger.error("Delete vm snapshot " + vmSnapshot.getName() + " of vm " + userVm.getInstanceName() + " failed due to " + answer.getDetails());
+                return false;
+            }
+        } catch (Exception e) {
+            String msg = "Delete vm snapshot " + vmSnapshot.getName() + " of vm " + userVm.getInstanceName() + " failed due to " + e.getMessage();
+            s_logger.error(msg , e);
+            throw new CloudRuntimeException(e.getMessage());
+        }
+    }
+
+    @Override
+    @ActionEvent(eventType = EventTypes.EVENT_VM_SNAPSHOT_REVERT, eventDescription = "revert to VM snapshot", async = true)
+    public UserVm revertToSnapshot(Long vmSnapshotId) throws InsufficientCapacityException, ResourceUnavailableException, ConcurrentOperationException {
+
+        // check if VM snapshot exists in DB
+        VMSnapshotVO vmSnapshotVo = _vmSnapshotDao.findById(vmSnapshotId);
+        if (vmSnapshotVo == null) {
+            throw new InvalidParameterValueException(
+                    "unable to find the vm snapshot with id " + vmSnapshotId);
+        }
+        Long vmId = vmSnapshotVo.getVmId();
+        UserVmVO userVm = _userVMDao.findById(vmId);
+        // check if VM exists
+        if (userVm == null) {
+            throw new InvalidParameterValueException("Revert vm to snapshot: "
+                    + vmSnapshotId + " failed due to vm: " + vmId
+                    + " is not found");
+        }
+        
+        // check if there are other active VM snapshot tasks
+        if (hasActiveVMSnapshotTasks(vmId)) {
+            throw new InvalidParameterValueException("There is other active vm snapshot tasks on the instance, please try again later");
+        }
+        
+        Account caller = getCaller();
+        _accountMgr.checkAccess(caller, null, true, vmSnapshotVo);
+
+        // VM should be in running or stopped states
+        if (userVm.getState() != VirtualMachine.State.Running
+                && userVm.getState() != VirtualMachine.State.Stopped) {
+            throw new InvalidParameterValueException(
+                    "VM Snapshot reverting failed due to vm is not in the state of Running or Stopped.");
+        }
+        
+        // if snapshot is not created, error out
+        if (vmSnapshotVo.getState() != VMSnapshot.State.Ready) {
+            throw new InvalidParameterValueException(
+                    "VM Snapshot reverting failed due to vm snapshot is not in the state of Created.");
+        }
+
+        UserVO callerUser = _userDao.findById(UserContext.current().getCallerUserId());
+        
+        UserVmVO vm = null;
+        Long hostId = null;
+        Account owner = _accountDao.findById(vmSnapshotVo.getAccountId());
+        
+        // start or stop VM first, if revert from stopped state to running state, or from running to stopped
+        if(userVm.getState() == VirtualMachine.State.Stopped && vmSnapshotVo.getType() == VMSnapshot.Type.DiskAndMemory){
+            try {
+        	    vm = _itMgr.advanceStart(userVm, new HashMap<VirtualMachineProfile.Param, Object>(), callerUser, owner);
+        	    hostId = vm.getHostId();
+        	} catch (Exception e) {
+        	    s_logger.error("Start VM " + userVm.getInstanceName() + " before reverting failed due to " + e.getMessage());
+        	    throw new CloudRuntimeException(e.getMessage());
+        	}
+        }else {
+            if(userVm.getState() == VirtualMachine.State.Running && vmSnapshotVo.getType() == VMSnapshot.Type.Disk){
+                try {
+    			    _itMgr.advanceStop(userVm, true, callerUser, owner);
+                } catch (Exception e) {
+                    s_logger.error("Stop VM " + userVm.getInstanceName() + " before reverting failed due to " + e.getMessage());
+    			    throw new CloudRuntimeException(e.getMessage());
+                }
+            }
+            hostId = pickRunningHost(userVm.getId());
+        }
+        
+        if(hostId == null)
+            throw new CloudRuntimeException("Can not find any host to revert snapshot " + vmSnapshotVo.getName());
+        
+        // check if there are other active VM snapshot tasks
+        if (hasActiveVMSnapshotTasks(userVm.getId())) {
+            throw new InvalidParameterValueException("There is other active vm snapshot tasks on the instance, please try again later");
+        }
+        
+        userVm = _userVMDao.findById(userVm.getId());
+        try {
+            vmSnapshotStateTransitTo(vmSnapshotVo, VMSnapshot.Event.RevertRequested);
+        } catch (NoTransitionException e) {
+            throw new CloudRuntimeException(e.getMessage());
+        }
+        return revertInternal(userVm, vmSnapshotVo, hostId);
+    }
+
+    private UserVm revertInternal(UserVmVO userVm, VMSnapshotVO vmSnapshotVo, Long hostId) {
+        try {
+            VMSnapshotVO snapshot = _vmSnapshotDao.findById(vmSnapshotVo.getId());
+            // prepare RevertToSnapshotCommand
+            List<VolumeTO> volumeTOs = getVolumeTOList(userVm.getId());
+            String vmInstanceName = userVm.getInstanceName();
+            VMSnapshotTO parent = getSnapshotWithParents(snapshot).getParent();
+            VMSnapshotTO vmSnapshotTO = new VMSnapshotTO(snapshot.getId(), snapshot.getName(), snapshot.getType(), 
+            		snapshot.getCreated().getTime(), snapshot.getDescription(), snapshot.getCurrent(), parent);
+            
+            GuestOSVO guestOS = _guestOSDao.findById(userVm.getGuestOSId());
+            RevertToVMSnapshotCommand revertToSnapshotCommand = new RevertToVMSnapshotCommand(vmInstanceName, vmSnapshotTO, volumeTOs, guestOS.getDisplayName());
+           
+            RevertToVMSnapshotAnswer answer = (RevertToVMSnapshotAnswer) sendToPool(hostId, revertToSnapshotCommand);
+            if (answer != null && answer.getResult()) {
+                processAnswer(vmSnapshotVo, userVm, answer, hostId);
+                s_logger.debug("RevertTo " + vmSnapshotVo.getName() + " succeeded for vm: " + userVm.getInstanceName());
+            } else {
+                String errMsg = "Revert VM: " + userVm.getInstanceName() + " to snapshot: "+ vmSnapshotVo.getName() + " failed";
+                if(answer != null && answer.getDetails() != null)
+                    errMsg = errMsg + " due to " + answer.getDetails();
+                s_logger.error(errMsg);
+                // agent report revert operation fails
+                vmSnapshotStateTransitTo(vmSnapshotVo, VMSnapshot.Event.OperationFailed);
+                throw new CloudRuntimeException(errMsg);
+            }
+        } catch (Exception e) {
+            if(e instanceof AgentUnavailableException){
+                try {
+                    vmSnapshotStateTransitTo(vmSnapshotVo, VMSnapshot.Event.OperationFailed);
+                } catch (NoTransitionException e1) {
+                    s_logger.error("Cannot set vm snapshot state due to: " + e1.getMessage());
+                }
+            }
+            // for other exceptions, do not change VM snapshot state, leave it for snapshotSync
+            String errMsg = "revert vm: " + userVm.getInstanceName() + " to snapshot " + vmSnapshotVo.getName() + " failed due to " + e.getMessage();
+            s_logger.error(errMsg);
+            throw new CloudRuntimeException(e.getMessage());
+        } 
+        return userVm;
+    }
+
+
+    @Override
+    public VMSnapshot getVMSnapshotById(Long id) {
+        VMSnapshotVO vmSnapshot = _vmSnapshotDao.findById(id);
+        return vmSnapshot;
+    }
+
+    protected Long pickRunningHost(Long vmId) {
+        UserVmVO vm = _userVMDao.findById(vmId);
+        // use VM's host if VM is running
+        if(vm.getState() == State.Running)
+            return vm.getHostId();
+        
+        // check if lastHostId is available
+        if(vm.getLastHostId() != null){
+           HostVO lastHost =  _hostDao.findById(vm.getLastHostId());
+           if(lastHost.getStatus() == com.cloud.host.Status.Up && !lastHost.isInMaintenanceStates())
+               return lastHost.getId();
+        }
+        
+        List<VolumeVO> listVolumes = _volumeDao.findByInstance(vmId);
+        if (listVolumes == null || listVolumes.size() == 0) {
+            throw new InvalidParameterValueException("vmInstance has no volumes");
+        }
+        VolumeVO volume = listVolumes.get(0);
+        Long poolId = volume.getPoolId();
+        if (poolId == null) {
+            throw new InvalidParameterValueException("pool id is not found");
+        }
+        StoragePoolVO storagePool = _storagePoolDao.findById(poolId);
+        if (storagePool == null) {
+            throw new InvalidParameterValueException("storage pool is not found");
+        }
+        List<HostVO> listHost = _hostDao.listAllUpAndEnabledNonHAHosts(Host.Type.Routing, storagePool.getClusterId(), storagePool.getPodId(),
+                storagePool.getDataCenterId(), null);
+        if (listHost == null || listHost.size() == 0) {
+            throw new InvalidParameterValueException("no host in up state is found");
+        }
+        return listHost.get(0).getId();
+    }
+
+    @Override
+    public VirtualMachine getVMBySnapshotId(Long id) {
+        VMSnapshotVO vmSnapshot = _vmSnapshotDao.findById(id);
+        if(vmSnapshot == null){
+            throw new InvalidParameterValueException("unable to find the vm snapshot with id " + id);
+        }
+        Long vmId = vmSnapshot.getVmId();
+        UserVmVO vm = _userVMDao.findById(vmId);
+        return vm;
+    }
+
+    @Override
+    public boolean deleteAllVMSnapshots(long vmId, VMSnapshot.Type type) {
+        boolean result = true;
+        List<VMSnapshotVO> listVmSnapshots = _vmSnapshotDao.findByVm(vmId);
+        if (listVmSnapshots == null || listVmSnapshots.isEmpty()) {
+            return true;
+        }
+        for (VMSnapshotVO snapshot : listVmSnapshots) {
+            VMSnapshotVO target = _vmSnapshotDao.findById(snapshot.getId());
+            if(type != null && target.getType() != type)
+                continue;
+            if (!deleteSnapshotInternal(target)) {
+                result = false;
+                break;
+            }
+        }
+        return result;
+    }
+
+    @Override
+    public boolean syncVMSnapshot(VMInstanceVO vm, Long hostId) {
+        try{
+            
+            UserVmVO userVm = _userVMDao.findById(vm.getId());
+            if(userVm == null)
+                return false;
+            
+            List<VMSnapshotVO> vmSnapshotsInExpungingStates = _vmSnapshotDao.listByInstanceId(vm.getId(), VMSnapshot.State.Expunging, VMSnapshot.State.Reverting, VMSnapshot.State.Creating);
+            for (VMSnapshotVO vmSnapshotVO : vmSnapshotsInExpungingStates) {
+                if(vmSnapshotVO.getState() == VMSnapshot.State.Expunging){
+                    return deleteSnapshotInternal(vmSnapshotVO);
+                }else if(vmSnapshotVO.getState() == VMSnapshot.State.Creating){
+                    return createVmSnapshotInternal(userVm, vmSnapshotVO, hostId) != null;
+                }else if(vmSnapshotVO.getState() == VMSnapshot.State.Reverting){
+                    return revertInternal(userVm, vmSnapshotVO, hostId) != null;
+                }
+            }
+        }catch (Exception e) {
+            s_logger.error(e.getMessage(),e);
+            if(_vmSnapshotDao.listByInstanceId(vm.getId(), VMSnapshot.State.Expunging).size() == 0)
+                return true;
+            else
+                return false;
+        }
+        return false;
+    }
+ 
+}

http://git-wip-us.apache.org/repos/asf/incubator-cloudstack/blob/9a12756a/server/src/com/cloud/vm/snapshot/dao/VMSnapshotDao.java
----------------------------------------------------------------------
diff --git a/server/src/com/cloud/vm/snapshot/dao/VMSnapshotDao.java b/server/src/com/cloud/vm/snapshot/dao/VMSnapshotDao.java
new file mode 100644
index 0000000..7532edf
--- /dev/null
+++ b/server/src/com/cloud/vm/snapshot/dao/VMSnapshotDao.java
@@ -0,0 +1,39 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+package com.cloud.vm.snapshot.dao;
+
+import java.util.List;
+
+import com.cloud.utils.db.GenericDao;
+import com.cloud.utils.fsm.StateDao;
+import com.cloud.vm.snapshot.VMSnapshot;
+import com.cloud.vm.snapshot.VMSnapshotVO;
+
+public interface VMSnapshotDao extends GenericDao<VMSnapshotVO, Long>, StateDao<VMSnapshot.State, VMSnapshot.Event, VMSnapshot> {
+
+    List<VMSnapshotVO> findByVm(Long vmId);
+
+    List<VMSnapshotVO> listExpungingSnapshot();
+
+    List<VMSnapshotVO> listByInstanceId(Long vmId, VMSnapshot.State... status);
+
+	VMSnapshotVO findCurrentSnapshotByVmId(Long vmId);
+	
+	List<VMSnapshotVO> listByParent(Long vmSnapshotId);
+	
+	VMSnapshotVO findByName(Long vm_id, String name);
+}

http://git-wip-us.apache.org/repos/asf/incubator-cloudstack/blob/9a12756a/server/src/com/cloud/vm/snapshot/dao/VMSnapshotDaoImpl.java
----------------------------------------------------------------------
diff --git a/server/src/com/cloud/vm/snapshot/dao/VMSnapshotDaoImpl.java b/server/src/com/cloud/vm/snapshot/dao/VMSnapshotDaoImpl.java
new file mode 100644
index 0000000..7d8ace7
--- /dev/null
+++ b/server/src/com/cloud/vm/snapshot/dao/VMSnapshotDaoImpl.java
@@ -0,0 +1,161 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package com.cloud.vm.snapshot.dao;
+
+import java.util.Date;
+import java.util.List;
+
+import javax.ejb.Local;
+
+import org.apache.log4j.Logger;
+import org.springframework.stereotype.Component;
+
+import com.cloud.utils.db.GenericDaoBase;
+import com.cloud.utils.db.SearchBuilder;
+import com.cloud.utils.db.SearchCriteria;
+import com.cloud.utils.db.SearchCriteria.Op;
+import com.cloud.utils.db.UpdateBuilder;
+import com.cloud.vm.snapshot.VMSnapshot;
+import com.cloud.vm.snapshot.VMSnapshot.Event;
+import com.cloud.vm.snapshot.VMSnapshot.State;
+import com.cloud.vm.snapshot.VMSnapshotVO;
+@Component
+@Local(value = { VMSnapshotDao.class })
+public class VMSnapshotDaoImpl extends GenericDaoBase<VMSnapshotVO, Long>
+        implements VMSnapshotDao {
+    private static final Logger s_logger = Logger.getLogger(VMSnapshotDaoImpl.class);
+    private final SearchBuilder<VMSnapshotVO> SnapshotSearch;
+    private final SearchBuilder<VMSnapshotVO> ExpungingSnapshotSearch;
+    private final SearchBuilder<VMSnapshotVO> SnapshotStatusSearch;
+    private final SearchBuilder<VMSnapshotVO> AllFieldsSearch;
+
+    protected VMSnapshotDaoImpl() {
+        AllFieldsSearch = createSearchBuilder();
+        AllFieldsSearch.and("state", AllFieldsSearch.entity().getState(), Op.EQ);
+        AllFieldsSearch.and("accountId", AllFieldsSearch.entity().getAccountId(), Op.EQ);
+        AllFieldsSearch.and("vm_id", AllFieldsSearch.entity().getVmId(), Op.EQ);
+        AllFieldsSearch.and("deviceId", AllFieldsSearch.entity().getVmId(), Op.EQ);
+        AllFieldsSearch.and("id", AllFieldsSearch.entity().getId(), Op.EQ);
+        AllFieldsSearch.and("removed", AllFieldsSearch.entity().getState(), Op.EQ);
+        AllFieldsSearch.and("parent", AllFieldsSearch.entity().getParent(), Op.EQ);
+        AllFieldsSearch.and("current", AllFieldsSearch.entity().getCurrent(), Op.EQ);
+        AllFieldsSearch.and("vm_snapshot_type", AllFieldsSearch.entity().getType(), Op.EQ);
+        AllFieldsSearch.and("updatedCount", AllFieldsSearch.entity().getUpdatedCount(), Op.EQ);
+        AllFieldsSearch.and("display_name", AllFieldsSearch.entity().getDisplayName(), SearchCriteria.Op.EQ);
+        AllFieldsSearch.and("name", AllFieldsSearch.entity().getName(), SearchCriteria.Op.EQ);
+        AllFieldsSearch.done();
+        
+        SnapshotSearch = createSearchBuilder();
+        SnapshotSearch.and("vm_id", SnapshotSearch.entity().getVmId(),
+                SearchCriteria.Op.EQ);
+        SnapshotSearch.done();
+
+        ExpungingSnapshotSearch = createSearchBuilder();
+        ExpungingSnapshotSearch.and("state", ExpungingSnapshotSearch.entity()
+                .getState(), SearchCriteria.Op.EQ);
+        ExpungingSnapshotSearch.and("removed", ExpungingSnapshotSearch.entity()
+                .getRemoved(), SearchCriteria.Op.NULL);
+        ExpungingSnapshotSearch.done();
+
+        SnapshotStatusSearch = createSearchBuilder();
+        SnapshotStatusSearch.and("vm_id", SnapshotStatusSearch.entity()
+                .getVmId(), SearchCriteria.Op.EQ);
+        SnapshotStatusSearch.and("state", SnapshotStatusSearch.entity()
+                .getState(), SearchCriteria.Op.IN);
+        SnapshotStatusSearch.done();
+    }
+
+    @Override
+    public List<VMSnapshotVO> findByVm(Long vmId) {
+        SearchCriteria<VMSnapshotVO> sc = SnapshotSearch.create();
+        sc.setParameters("vm_id", vmId);
+        return listBy(sc, null);
+    }
+
+    @Override
+    public List<VMSnapshotVO> listExpungingSnapshot() {
+        SearchCriteria<VMSnapshotVO> sc = ExpungingSnapshotSearch.create();
+        sc.setParameters("state", State.Expunging);
+        return listBy(sc, null);
+    }
+
+    @Override
+    public List<VMSnapshotVO> listByInstanceId(Long vmId, State... status) {
+        SearchCriteria<VMSnapshotVO> sc = SnapshotStatusSearch.create();
+        sc.setParameters("vm_id", vmId);
+        sc.setParameters("state", (Object[]) status);
+        return listBy(sc, null);
+    }
+
+	@Override
+	public VMSnapshotVO findCurrentSnapshotByVmId(Long vmId) {
+        SearchCriteria<VMSnapshotVO> sc = AllFieldsSearch.create();
+        sc.setParameters("vm_id", vmId);
+        sc.setParameters("current", 1);
+        return findOneBy(sc);
+	}
+
+    @Override
+    public List<VMSnapshotVO> listByParent(Long vmSnapshotId) {
+        SearchCriteria<VMSnapshotVO> sc = AllFieldsSearch.create();
+        sc.setParameters("parent", vmSnapshotId);
+        sc.setParameters("state", State.Ready );
+        return listBy(sc, null);
+    }
+
+    @Override
+    public VMSnapshotVO findByName(Long vm_id, String name) {
+        SearchCriteria<VMSnapshotVO> sc = AllFieldsSearch.create();
+        sc.setParameters("vm_id", vm_id);
+        sc.setParameters("display_name", name );
+        return null;
+    }
+
+    @Override
+    public boolean updateState(State currentState, Event event, State nextState, VMSnapshot vo, Object data) {
+        
+        Long oldUpdated = vo.getUpdatedCount();
+        Date oldUpdatedTime = vo.getUpdated();
+        
+        SearchCriteria<VMSnapshotVO> sc = AllFieldsSearch.create();
+        sc.setParameters("id", vo.getId());
+        sc.setParameters("state", currentState);
+        sc.setParameters("updatedCount", vo.getUpdatedCount());
+        
+        vo.incrUpdatedCount();
+        
+        UpdateBuilder builder = getUpdateBuilder(vo);
+        builder.set(vo, "state", nextState);
+        builder.set(vo, "updated", new Date());
+        
+        int rows = update((VMSnapshotVO)vo, sc);
+        if (rows == 0 && s_logger.isDebugEnabled()) {
+            VMSnapshotVO dbVol = findByIdIncludingRemoved(vo.getId()); 
+            if (dbVol != null) {
+                StringBuilder str = new StringBuilder("Unable to update ").append(vo.toString());
+                str.append(": DB Data={id=").append(dbVol.getId()).append("; state=").append(dbVol.getState()).append("; updatecount=").append(dbVol.getUpdatedCount()).append(";updatedTime=").append(dbVol.getUpdated());
+                str.append(": New Data={id=").append(vo.getId()).append("; state=").append(nextState).append("; event=").append(event).append("; updatecount=").append(vo.getUpdatedCount()).append("; updatedTime=").append(vo.getUpdated());
+                str.append(": stale Data={id=").append(vo.getId()).append("; state=").append(currentState).append("; event=").append(event).append("; updatecount=").append(oldUpdated).append("; updatedTime=").append(oldUpdatedTime);
+            } else {
+                s_logger.debug("Unable to update VM snapshot: id=" + vo.getId() + ", as there is no such snapshot exists in the database anymore");
+            }
+        }
+        return rows > 0;
+    }
+
+}

http://git-wip-us.apache.org/repos/asf/incubator-cloudstack/blob/9a12756a/server/test/com/cloud/vm/snapshot/VMSnapshotManagerTest.java
----------------------------------------------------------------------
diff --git a/server/test/com/cloud/vm/snapshot/VMSnapshotManagerTest.java b/server/test/com/cloud/vm/snapshot/VMSnapshotManagerTest.java
new file mode 100644
index 0000000..6fc6404
--- /dev/null
+++ b/server/test/com/cloud/vm/snapshot/VMSnapshotManagerTest.java
@@ -0,0 +1,186 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+package com.cloud.vm.snapshot;
+
+import static org.mockito.Matchers.any;
+import static org.mockito.Matchers.anyLong;
+import static org.mockito.Matchers.anyString;
+import static org.mockito.Mockito.doNothing;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.cloudstack.acl.ControlledEntity;
+import org.apache.cloudstack.acl.SecurityChecker.AccessType;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.mockito.Spy;
+
+import com.cloud.agent.AgentManager;
+import com.cloud.agent.api.Answer;
+import com.cloud.agent.api.CreateVMSnapshotAnswer;
+import com.cloud.agent.api.CreateVMSnapshotCommand;
+import com.cloud.agent.api.to.VolumeTO;
+import com.cloud.configuration.dao.ConfigurationDao;
+import com.cloud.exception.AgentUnavailableException;
+import com.cloud.exception.InvalidParameterValueException;
+import com.cloud.exception.OperationTimedoutException;
+import com.cloud.exception.ResourceAllocationException;
+import com.cloud.host.dao.HostDao;
+import com.cloud.hypervisor.HypervisorGuruManager;
+import com.cloud.storage.GuestOSVO;
+import com.cloud.storage.Snapshot;
+import com.cloud.storage.SnapshotVO;
+import com.cloud.storage.VolumeVO;
+import com.cloud.storage.dao.GuestOSDao;
+import com.cloud.storage.dao.SnapshotDao;
+import com.cloud.storage.dao.StoragePoolDao;
+import com.cloud.storage.dao.VolumeDao;
+import com.cloud.user.Account;
+import com.cloud.user.AccountManager;
+import com.cloud.user.dao.AccountDao;
+import com.cloud.user.dao.UserDao;
+import com.cloud.utils.exception.CloudRuntimeException;
+import com.cloud.utils.fsm.NoTransitionException;
+import com.cloud.vm.UserVmVO;
+import com.cloud.vm.VirtualMachine.State;
+import com.cloud.vm.VirtualMachineManager;
+import com.cloud.vm.dao.UserVmDao;
+import com.cloud.vm.dao.VMInstanceDao;
+import com.cloud.vm.snapshot.dao.VMSnapshotDao;
+
+
+
+public class VMSnapshotManagerTest {
+    @Spy VMSnapshotManagerImpl _vmSnapshotMgr = new VMSnapshotManagerImpl();
+    @Mock Account admin;
+    @Mock VMSnapshotDao _vmSnapshotDao;
+    @Mock VolumeDao _volumeDao;
+    @Mock AccountDao _accountDao;
+    @Mock VMInstanceDao _vmInstanceDao;
+    @Mock UserVmDao _userVMDao;
+    @Mock HostDao _hostDao;
+    @Mock UserDao _userDao;
+    @Mock AgentManager _agentMgr;
+    @Mock HypervisorGuruManager _hvGuruMgr;
+    @Mock AccountManager _accountMgr;
+    @Mock GuestOSDao _guestOSDao;
+    @Mock StoragePoolDao _storagePoolDao;
+    @Mock SnapshotDao _snapshotDao;
+    @Mock VirtualMachineManager _itMgr;
+    @Mock ConfigurationDao _configDao;
+    int _vmSnapshotMax = 10;
+    
+    private static long TEST_VM_ID = 3L;
+    @Mock UserVmVO vmMock;
+    @Mock VolumeVO volumeMock;
+    
+    @Before
+    public void setup(){
+        MockitoAnnotations.initMocks(this);
+        doReturn(admin).when(_vmSnapshotMgr).getCaller();
+        _vmSnapshotMgr._accountDao = _accountDao;
+        _vmSnapshotMgr._userVMDao = _userVMDao;
+        _vmSnapshotMgr._vmSnapshotDao = _vmSnapshotDao;
+        _vmSnapshotMgr._volumeDao = _volumeDao;
+        _vmSnapshotMgr._accountMgr = _accountMgr;
+        _vmSnapshotMgr._snapshotDao = _snapshotDao;
+        _vmSnapshotMgr._guestOSDao = _guestOSDao;
+        
+        doNothing().when(_accountMgr).checkAccess(any(Account.class), any(AccessType.class), 
+                any(Boolean.class), any(ControlledEntity.class));
+        
+        _vmSnapshotMgr._vmSnapshotMax = _vmSnapshotMax;
+        
+        when(_userVMDao.findById(anyLong())).thenReturn(vmMock);
+        when(_vmSnapshotDao.findByName(anyLong(), anyString())).thenReturn(null);
+        when(_vmSnapshotDao.findByVm(anyLong())).thenReturn(new ArrayList<VMSnapshotVO>());
+       
+        List<VolumeVO> mockVolumeList = new ArrayList<VolumeVO>();
+        mockVolumeList.add(volumeMock);
+        when(volumeMock.getInstanceId()).thenReturn(TEST_VM_ID);
+        when(_volumeDao.findByInstance(anyLong())).thenReturn(mockVolumeList);
+        
+        when(vmMock.getInstanceName()).thenReturn("i-3-VM-TEST");
+        when(vmMock.getState()).thenReturn(State.Running);
+        
+        when(_guestOSDao.findById(anyLong())).thenReturn(mock(GuestOSVO.class));
+    } 
+    
+    // vmId null case
+    @Test(expected=InvalidParameterValueException.class)
+    public void testAllocVMSnapshotF1() throws ResourceAllocationException{
+        when(_userVMDao.findById(TEST_VM_ID)).thenReturn(null);
+        _vmSnapshotMgr.allocVMSnapshot(TEST_VM_ID,"","",true);
+    }
+
+    // vm state not in [running, stopped] case
+    @Test(expected=InvalidParameterValueException.class)
+    public void testAllocVMSnapshotF2() throws ResourceAllocationException{
+        when(vmMock.getState()).thenReturn(State.Starting);
+        _vmSnapshotMgr.allocVMSnapshot(TEST_VM_ID,"","",true);
+    }
+    
+    // VM in stopped state & snapshotmemory case
+    @Test(expected=InvalidParameterValueException.class)
+    public void testCreateVMSnapshotF3() throws AgentUnavailableException, OperationTimedoutException, ResourceAllocationException{
+        when(vmMock.getState()).thenReturn(State.Stopped);
+        _vmSnapshotMgr.allocVMSnapshot(TEST_VM_ID,"","",true);
+    }
+    
+    // max snapshot limit case
+    @SuppressWarnings("unchecked")
+    @Test(expected=CloudRuntimeException.class)
+    public void testAllocVMSnapshotF4() throws ResourceAllocationException{
+        List<VMSnapshotVO> mockList = mock(List.class);
+        when(mockList.size()).thenReturn(10);
+        when(_vmSnapshotDao.findByVm(TEST_VM_ID)).thenReturn(mockList);
+        _vmSnapshotMgr.allocVMSnapshot(TEST_VM_ID,"","",true);
+    }
+    
+    // active volume snapshots case
+    @SuppressWarnings("unchecked")
+    @Test(expected=CloudRuntimeException.class)
+    public void testAllocVMSnapshotF5() throws ResourceAllocationException{
+        List<SnapshotVO> mockList = mock(List.class);
+        when(mockList.size()).thenReturn(1);
+        when(_snapshotDao.listByInstanceId(TEST_VM_ID,Snapshot.State.Creating,
+                Snapshot.State.CreatedOnPrimary, Snapshot.State.BackingUp)).thenReturn(mockList);
+        _vmSnapshotMgr.allocVMSnapshot(TEST_VM_ID,"","",true);
+    }
+    
+    // successful creation case
+    @Test
+    public void testCreateVMSnapshot() throws AgentUnavailableException, OperationTimedoutException, ResourceAllocationException, NoTransitionException{
+        when(vmMock.getState()).thenReturn(State.Running);
+        _vmSnapshotMgr.allocVMSnapshot(TEST_VM_ID,"","",true);
+        
+        when(_vmSnapshotDao.findCurrentSnapshotByVmId(anyLong())).thenReturn(null);
+        doReturn(new ArrayList<VolumeTO>()).when(_vmSnapshotMgr).getVolumeTOList(anyLong());
+        doReturn(new CreateVMSnapshotAnswer(null,true,"")).when(_vmSnapshotMgr).sendToPool(anyLong(), any(CreateVMSnapshotCommand.class));
+        doNothing().when(_vmSnapshotMgr).processAnswer(any(VMSnapshotVO.class), 
+                any(UserVmVO.class), any(Answer.class), anyLong());
+        doReturn(true).when(_vmSnapshotMgr).vmSnapshotStateTransitTo(any(VMSnapshotVO.class),any(VMSnapshot.Event.class));
+        _vmSnapshotMgr.createVmSnapshotInternal(vmMock, mock(VMSnapshotVO.class), 5L);
+    }
+
+}

http://git-wip-us.apache.org/repos/asf/incubator-cloudstack/blob/9a12756a/setup/db/create-schema.sql
----------------------------------------------------------------------
diff --git a/setup/db/create-schema.sql b/setup/db/create-schema.sql
index f89c885..11ae267 100755
--- a/setup/db/create-schema.sql
+++ b/setup/db/create-schema.sql
@@ -2625,6 +2625,36 @@ INSERT INTO `cloud`.`counter` (id, uuid, source, name, value,created) VALUES (1,
 INSERT INTO `cloud`.`counter` (id, uuid, source, name, value,created) VALUES (2, UUID(), 'snmp','Linux System CPU - percentage', '1.3.6.1.4.1.2021.11.10.0', now());
 INSERT INTO `cloud`.`counter` (id, uuid, source, name, value,created) VALUES (3, UUID(), 'snmp','Linux CPU Idle - percentage', '1.3.6.1.4.1.2021.11.11.0', now());
 INSERT INTO `cloud`.`counter` (id, uuid, source, name, value,created) VALUES (100, UUID(), 'netscaler','Response Time - microseconds', 'RESPTIME', now());
+CREATE TABLE `cloud`.`vm_snapshots` (
+  `id` bigint(20) unsigned NOT NULL auto_increment COMMENT 'Primary Key',
+  `uuid` varchar(40) NOT NULL,
+  `name` varchar(255) NOT NULL,
+  `display_name` varchar(255) default NULL,
+  `description` varchar(255) default NULL,
+  `vm_id` bigint(20) unsigned NOT NULL,
+  `account_id` bigint(20) unsigned NOT NULL,
+  `domain_id` bigint(20) unsigned NOT NULL,
+  `vm_snapshot_type` varchar(32) default NULL,
+  `state` varchar(32) NOT NULL,
+  `parent` bigint unsigned default NULL,
+  `current` int(1) unsigned default NULL,
+  `update_count` bigint unsigned NOT NULL DEFAULT 0,
+  `updated` datetime default NULL,
+  `created` datetime default NULL,
+  `removed` datetime default NULL,
+  PRIMARY KEY  (`id`),
+  CONSTRAINT UNIQUE KEY `uc_vm_snapshots_uuid` (`uuid`),
+  INDEX `vm_snapshots_name` (`name`),
+  INDEX `vm_snapshots_vm_id` (`vm_id`),
+  INDEX `vm_snapshots_account_id` (`account_id`),
+  INDEX `vm_snapshots_display_name` (`display_name`),
+  INDEX `vm_snapshots_removed` (`removed`),
+  INDEX `vm_snapshots_parent` (`parent`),
+  CONSTRAINT `fk_vm_snapshots_vm_id__vm_instance_id` FOREIGN KEY `fk_vm_snapshots_vm_id__vm_instance_id` (`vm_id`) REFERENCES `vm_instance` (`id`),
+  CONSTRAINT `fk_vm_snapshots_account_id__account_id` FOREIGN KEY `fk_vm_snapshots_account_id__account_id` (`account_id`) REFERENCES `account` (`id`),
+  CONSTRAINT `fk_vm_snapshots_domain_id__domain_id` FOREIGN KEY `fk_vm_snapshots_domain_id__domain_id` (`domain_id`) REFERENCES `domain` (`id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8;
+
 
 CREATE TABLE  `cloud`.`user_ipv6_address` (
   `id` bigint unsigned NOT NULL UNIQUE auto_increment,

http://git-wip-us.apache.org/repos/asf/incubator-cloudstack/blob/9a12756a/ui/css/cloudstack3.css
----------------------------------------------------------------------
diff --git a/ui/css/cloudstack3.css b/ui/css/cloudstack3.css
index 6cb82f2..42cd783 100644
--- a/ui/css/cloudstack3.css
+++ b/ui/css/cloudstack3.css
@@ -1931,7 +1931,7 @@ div.detail-group.actions td {
 }
 
 .detail-group table td.detail-actions {
-  width: 55%;
+  width: 59%;
   height: 26px;
 }
 

http://git-wip-us.apache.org/repos/asf/incubator-cloudstack/blob/9a12756a/ui/dictionary.jsp
----------------------------------------------------------------------
diff --git a/ui/dictionary.jsp b/ui/dictionary.jsp
index 5081356..2abafaa 100644
--- a/ui/dictionary.jsp
+++ b/ui/dictionary.jsp
@@ -1437,6 +1437,16 @@ dictionary = {
 'label.resize.new.size': '<fmt:message key="label.resize.new.size" />',
 'label.action.resize.volume': '<fmt:message key="label.action.resize.volume" />',
 'label.resize.new.offering.id': '<fmt:message key="label.resize.new.offering.id" />',
-'label.resize.shrink.ok': '<fmt:message key="label.resize.shrink.ok" />'
+'label.resize.shrink.ok': '<fmt:message key="label.resize.shrink.ok" />',
+'label.vmsnapshot.current': '<fmt:message key="label.vmsnapshot.current" />',
+'label.vmsnapshot.parentname': '<fmt:message key="label.vmsnapshot.parentname" />',
+'label.vmsnapshot.type': '<fmt:message key="label.vmsnapshot.type" />',
+'label.vmsnapshot.memory': '<fmt:message key="label.vmsnapshot.memory" />',
+'label.vmsnapshot': '<fmt:message key="label.vmsnapshot" />',
+'label.action.vmsnapshot.create': '<fmt:message key="label.action.vmsnapshot.create" />',
+'label.action.vmsnapshot.delete': '<fmt:message key="label.action.vmsnapshot.delete" />',
+'label.action.vmsnapshot.revert': '<fmt:message key="label.action.vmsnapshot.revert" />',
+'message.action.vmsnapshot.delete': '<fmt:message key="message.action.vmsnapshot.delete" />',
+'message.action.vmsnapshot.revert': '<fmt:message key="message.action.vmsnapshot.revert" />'
 };
 </script>

http://git-wip-us.apache.org/repos/asf/incubator-cloudstack/blob/9a12756a/ui/index.jsp
----------------------------------------------------------------------
diff --git a/ui/index.jsp b/ui/index.jsp
index fdacd9e..8af1478 100644
--- a/ui/index.jsp
+++ b/ui/index.jsp
@@ -1674,6 +1674,8 @@ under the License.
     <script type="text/javascript" src="scripts/system.js?t=<%=now%>"></script>
     <script type="text/javascript" src="scripts/domains.js?t=<%=now%>"></script>
     <script type="text/javascript" src="scripts/docs.js?t=<%=now%>"></script>
+    <script type="text/javascript" src="scripts/domains.js?t=<%=now%>"></script>   
+    <script type="text/javascript" src="scripts/vm_snapshots.js?t=<%=now%>"></script>  
   </body>
 </html>
 <jsp:include page="dictionary.jsp" />

http://git-wip-us.apache.org/repos/asf/incubator-cloudstack/blob/9a12756a/ui/scripts/instances.js
----------------------------------------------------------------------
diff --git a/ui/scripts/instances.js b/ui/scripts/instances.js
index 5b5ed18..264b5a1 100644
--- a/ui/scripts/instances.js
+++ b/ui/scripts/instances.js
@@ -48,7 +48,7 @@
 				displayname: { label: 'label.display.name' },
         zonename: { label: 'label.zone.name' },
         state: {
-          label: 'label.state',         
+          label: 'label.state',
           indicator: {
             'Running': 'on',
             'Stopped': 'off',
@@ -153,6 +153,194 @@
           notification: {
             poll: pollAsyncJobResult
           }
+        },
+        start: {
+          label: 'label.action.start.instance' ,
+          action: function(args) {
+            $.ajax({
+              url: createURL("startVirtualMachine&id=" + args.context.instances[0].id),
+              dataType: "json",
+              async: true,
+              success: function(json) {
+                var jid = json.startvirtualmachineresponse.jobid;
+                args.response.success(
+                  {_custom:
+                   {jobId: jid,
+                    getUpdatedItem: function(json) {
+                      return json.queryasyncjobresultresponse.jobresult.virtualmachine;
+                    },
+                    getActionFilter: function() {
+                      return vmActionfilter;
+                    }
+                   }
+                  }
+                );
+              }
+            });
+          },
+          messages: {
+            confirm: function(args) {
+              return 'message.action.start.instance';
+            },
+            notification: function(args) {
+              return 'label.action.start.instance';
+            },
+						complete: function(args) {						  
+							if(args.password != null) {
+								alert('Password of the VM is ' + args.password);
+							}
+							return 'label.action.start.instance';
+						}			
+          },
+          notification: {
+            poll: pollAsyncJobResult
+          }
+        },
+        stop: {
+          label: 'label.action.stop.instance',
+          addRow: 'false',
+          createForm: {
+            title: 'label.action.stop.instance',
+            desc: 'message.action.stop.instance',
+            fields: {
+              forced: {
+                label: 'force.stop',
+                isBoolean: true,
+                isChecked: false
+              }
+            }
+          },
+          action: function(args) {
+            var array1 = [];
+            array1.push("&forced=" + (args.data.forced == "on"));
+            $.ajax({
+              url: createURL("stopVirtualMachine&id=" + args.context.instances[0].id + array1.join("")),
+              dataType: "json",
+              async: true,
+              success: function(json) {
+                var jid = json.stopvirtualmachineresponse.jobid;
+                args.response.success(
+                  {_custom:
+                   {jobId: jid,
+                    getUpdatedItem: function(json) {
+                      return json.queryasyncjobresultresponse.jobresult.virtualmachine;
+                    },
+                    getActionFilter: function() {
+                      return vmActionfilter;
+                    }
+                   }
+                  }
+                );
+              }
+            });
+          },
+          messages: {
+            confirm: function(args) {
+              return 'message.action.stop.instance';
+            },
+
+            notification: function(args) {
+              return 'label.action.stop.instance';
+            }
+          },
+          notification: {
+            poll: pollAsyncJobResult
+          }
+        },
+        restart: {
+          label: 'instances.actions.reboot.label',
+          action: function(args) {
+            $.ajax({
+              url: createURL("rebootVirtualMachine&id=" + args.context.instances[0].id),
+              dataType: "json",
+              async: true,
+              success: function(json) {
+                var jid = json.rebootvirtualmachineresponse.jobid;
+                args.response.success(
+                  {_custom:
+                   {jobId: jid,
+                    getUpdatedItem: function(json) {
+                      return json.queryasyncjobresultresponse.jobresult.virtualmachine;
+                    },
+                    getActionFilter: function() {
+                      return vmActionfilter;
+                    }
+                   }
+                  }
+                );
+              }
+            });
+          },
+          messages: {
+            confirm: function(args) {
+              return 'message.action.reboot.instance';
+            },
+            notification: function(args) {
+              return 'instances.actions.reboot.label';
+            }
+          },
+          notification: {
+            poll: pollAsyncJobResult
+          }
+        },
+
+        destroy: {
+          label: 'label.action.destroy.instance',
+          messages: {
+            confirm: function(args) {
+              return 'message.action.destroy.instance';
+            },            
+            notification: function(args) {
+              return 'label.action.destroy.instance';
+            }
+          },
+          action: function(args) {
+            $.ajax({
+              url: createURL("destroyVirtualMachine&id=" + args.context.instances[0].id),
+              dataType: "json",
+              async: true,
+              success: function(json) {
+                var jid = json.destroyvirtualmachineresponse.jobid;
+                args.response.success(
+                  {_custom:
+                   {jobId: jid,
+                    getUpdatedItem: function(json) {
+                      return json.queryasyncjobresultresponse.jobresult.virtualmachine;
+                    },
+                    getActionFilter: function() {
+                      return vmActionfilter;
+                    }
+                   }
+                  }
+                );
+              }
+            });
+          },
+          notification: {
+            poll: pollAsyncJobResult
+          }
+        },
+        restore: {     
+					label: 'label.action.restore.instance',
+					messages: {
+						confirm: function(args) {
+							return 'message.action.restore.instance';
+						},
+						notification: function(args) {
+							return 'label.action.restore.instance';
+						}
+					},					
+          action: function(args) {
+            $.ajax({
+              url: createURL("recoverVirtualMachine&id=" + args.context.instances[0].id),
+              dataType: "json",
+              async: true,
+              success: function(json) {
+                var item = json.recovervirtualmachineresponse.virtualmachine;
+                args.response.success({data:item});
+              }
+            });
+          }
         }
       },
 
@@ -231,7 +419,7 @@
 
       detailView: {
         name: 'Instance details',
-        viewAll: { path: 'storage.volumes', label: 'label.volumes' },
+        viewAll: [{ path: 'storage.volumes', label: 'label.volumes' }, { path: 'vmsnapshots', label: 'Snapshots' } ],
         tabFilter: function(args) {
           var hiddenTabs = [];
 					
@@ -409,6 +597,70 @@
               poll: pollAsyncJobResult
             }
           },
+
+          snapshot: {
+            messages: {
+              notification: function(args) {
+                return 'label.action.vmsnapshot.create';
+              }
+            },
+            label: 'label.action.vmsnapshot.create',
+            addRow: 'false',
+            createForm: {
+              title: 'label.action.vmsnapshot.create',
+              fields: {
+                name: {
+                  label: 'label.name',
+                  isInput: true
+                },
+                description: {
+                  label: 'label.description',
+                  isTextarea: true
+                },
+                snapshotMemory: {
+                  label: 'label.vmsnapshot.memory',
+                  isBoolean: true,
+                  isChecked: false
+                }
+              }
+            },
+            action: function(args) {
+              var array1 = [];
+              array1.push("&snapshotmemory=" + (args.data.snapshotMemory == "on"));
+              var displayname = args.data.name;
+              if (displayname != null && displayname.length > 0) {
+                array1.push("&name=" + todb(displayname));
+              }
+              var description = args.data.description;
+              if (description != null && description.length > 0) {
+                array1.push("&description=" + todb(description));
+              }
+              $.ajax({
+                url: createURL("createVMSnapshot&virtualmachineid=" + args.context.instances[0].id + array1.join("")),
+                dataType: "json",
+                async: true,
+                success: function(json) {
+                  var jid = json.createvmsnapshotresponse.jobid;
+                  args.response.success({
+                    _custom: {
+                      jobId: jid,
+                      getUpdatedItem: function(json) {
+                        return json.queryasyncjobresultresponse.jobresult.virtualmachine;
+                      },
+                      getActionFilter: function() {
+                        return vmActionfilter;
+                      }
+                    }
+                  });
+                }
+              });
+          
+            },
+            notification: {
+              pool: pollAsyncJobResult
+            }
+          },          
+
           destroy: {
             label: 'label.action.destroy.instance',
             compactLabel: 'label.destroy',
@@ -1232,6 +1484,7 @@
     else if (jsonObj.state == 'Running') {     
       allowedActions.push("stop");
       allowedActions.push("restart");
+      allowedActions.push("snapshot");
       allowedActions.push("destroy");
       allowedActions.push("changeService");
       allowedActions.push("reset");
@@ -1257,7 +1510,7 @@
       allowedActions.push("start");
       allowedActions.push("destroy");
       allowedActions.push("reset");
-
+      allowedActions.push("snapshot");
       if(isAdmin())
         allowedActions.push("migrateToAnotherStorage");
 

http://git-wip-us.apache.org/repos/asf/incubator-cloudstack/blob/9a12756a/ui/scripts/ui/widgets/detailView.js
----------------------------------------------------------------------
diff --git a/ui/scripts/ui/widgets/detailView.js b/ui/scripts/ui/widgets/detailView.js
index 4b4fbd5..5f0c0f0 100644
--- a/ui/scripts/ui/widgets/detailView.js
+++ b/ui/scripts/ui/widgets/detailView.js
@@ -892,14 +892,20 @@
         $actions.prependTo($firstRow.closest('div.detail-group').closest('.details'));
       }
       if (detailViewArgs.viewAll && showViewAll) {
+       
+      if( !(detailViewArgs.viewAll instanceof Array)){
+       	detailViewArgs.viewAll = [detailViewArgs.viewAll];
+      }
+      $.each(detailViewArgs.viewAll, function(n, view){
         $('<div>')
           .addClass('view-all')
           .append(
             $('<a>')
               .attr({ href: '#' })
-              .data('detail-view-link-view-all', detailViewArgs.viewAll)
+              .css('padding','0 1px')
+              .data('detail-view-link-view-all', view)
               .append(
-                $('<span>').html(_l('label.view') + ' ' + _l(detailViewArgs.viewAll.label))
+                $('<span>').html(_l('label.view') + ' ' + _l(view.label))
               )
           )
           .append(
@@ -908,9 +914,10 @@
           .appendTo(
             $('<td>')
               .addClass('view-all')
+              .css('padding','9px 3px 8px 0')
               .appendTo($actions.find('tr'))
           );
-
+        });
       }
     }