June 10, 2013 XenClient Enterprise 5.0 Synchronizer and Hyper-V

June 10, 2013

XenClient Enterprise 5.0Synchronizer and Hyper-V

Copyright 2013 CitrixPage 2


Table of Contents

Synchronizer / Hyper-V Overview Page 3

Local vs. Remote Virtual Desktops Page 4

Server-Side Virtualization: VDI vs. XCE Page 5

Hyper-V Notes Page 6

Supported Windows Server and Hyper-V Versions Page 7

Hyper-V and Synchronizer Functionality Page 8

Hyper-V and the VM Image Lifecycle Page 9

Authoring Page 10

VM Shutdown Page 11

Publishing Page 12

Virtual Appliance Mode Page 13

Synchronizer Installation Methods Page 14

Synchronizer Share: Synchronizer View Page 15

Synchronizer Share: Hyper-V View Page 16

Virtual Appliance Mode and Synchronizer Backups Page 17

Loss of Hyper-V Services Page 18

Hyper-V in VMWare Environments Page 19

Preparing Hyper-V for Synchronizer Page 20

Preparing Hyper-V for Synchronizer Page 21

Hyper-V Integration Account Page 22

Hyper-V Server Local Administrators Group Page 23

Hyper-V Privileges: Windows Server 2008 R2 Page 24

Hyper-V Privileges: Windows Server 2012 Page 25

Hyper-V Functional Verification Page 26

Hyper-V Configuration Page 27

Hyper-V Detection During Synchronizer Installation Page 28

Hyper-V Configuration During Synchronizer Installation Page 29

Hyper-V Configuration in Synchronizer Console Page 30

Virtual Appliance Configuration Page 31

Hyper-V Virtual Network Page 32

Virtual Appliance Activation Page 33

When to Reactivate the Virtual Appliance Page 34

Hyper-V Sharing Page 35

Hyper-V Sharing Page 36

Hyper-V Sharing: Synchronizer Configuration Page 37

Hyper-V Sharing: Hyper-V Manager Page 38

Common Hyper-V Problems Page 39

Insufficient Memory Page 40

Hyper-V Connection Failure Page 41

Hyper-V Authentication or Authorization Failure Page 42

Virtual Network Not Found Page 43

Synchronizer Shared Folder Permissions Page 44

Hypervisor Not Running Page 45

Synchronizer / Hyper-V Overview



Local vs. Remote Virtual DesktopsClient Server

Citrix Receiver

VM VHD

XenServer

Local Desktops with XenClient Enterprise

•Synchronizer manages VHD files for VMs that can be deployed to Engine.

•Engine downloads VHD files and installs a local VM using local CPU, memory, and other resources.

•User has direct access to the desktop of the deployed VM.

•Once the VM is deployed, it will run on Engine without a network connection to Synchronizer.

VHD

XCE Synchronizer

VHDVM

XCE Engine

Remote Desktops with XenServer

•VM runs on a remote XenServer, booting from a VHD file.

•Citrix Receiver runs on the client and connects to the remote VM.

•Citrix Receiver delivers desktop of remove VM to the user.

•A constant network connection is required between the client and XenServer.



Server-Side Virtualization: VDI vs. XCE

Remote Virtual Desktops (VDI):

•Remote desktop VMs run on virtual infrastructure (XenServer) in the network datacenter.

•Clients use remote access software (Citrix Receiver) for virtual desktop connections.

•Server-side virtualization infrastructure is critical for user access to virtual desktops.

XenClient Enterprise Virtual Desktops:

•Primary virtualization platform is the XCE Engine.

•Deployed VMs run locally, using local resources, with direct access to the VM desktop.

•Deployed VMs have no dependency on any kind of server-side virtualization infrastructure.

•But Synchronizer uses Hyper-V as a tool for authoring and publishing VM images.

Important Distinction:

•Synchronizer only uses Hyper-V to manage VM images (authoring and publishing).

•Not to run VMs for user access to virtual desktops.



Hyper-V Notes

Primary vs. Remote Synchronizer Servers

•Synchronizer may be configured with one primary server and many remote servers.

•Only the primary server uses Hyper-V. Remote servers do not user Hyper-V at all.

Hyper-V and Native Windows

•Hyper-V requires native Windows, it won’t run in a VM (nested virtualization isn’t supported).

•Therefore the primary Synchronizer server needs a native Windows server.

•This can sometimes present challenges in fully virtualized environments.

•Virtual appliance installation is usually an acceptable solution.

Hyper-V Integration Methods

•Native: This means installing Synchronizer into a native (non-VM) Windows server with the Hyper-V role enabled. This is the most common installation option.

•Virtual Appliance: This means installing Synchronizer in a VM, then integrating with Hyper-V running elsewhere. Typically used in VMWare or XenServer environments, or when Hyper-V is in use for other purposes besides Synchronizer.



Supported Windows Server and Hyper-V Versions

• XCE Synchronizer version 5.0 supports:

• Windows Server 2008 R2

• Windows Server 2012

• Previous versions of Synchronizer only supported Windows Server 2008 R2.

• For Synchronizer installed in a VM (virtual appliance mode):

• Synchronizer integrates with a separate Hyper-V server.

• The Synchronizer VM and the Hyper-V server must run the same version of Windows.

• If Synchronizer is installed in a Windows Server 2008 R2 VM, then it must integrate with a separate Windows Server 2008 R2 Hyper-V server.

• If Synchronizer is installed in a Windows Serve 2012 VM, then it must integrate with a separate Windows Server 2012 Hyper-V server.



Hyper-V and Synchronizer Functionality

• Only the Virtual Machines section uses Hyper-V.

• All other sections (Users, Computers, Policies, etc.) don’t use Hyper-V and will remain fully functional if Hyper-V is not available.

• Within the Virtual Machines section, only the Start and Publish actions use Hyper-V.

• Other actions (Create, Clone, etc.) don’t use Hyper-V and will remain functional if Hyper-V is not available.

• The Attach ISO action will work without Hyper-V but it isn’t useful since the VM can’t be started.



Hyper-V and the VM Image Lifecycle

These operations use Hyper-V.

These operations do not use Hyper-V.

Author Installing the OS, applying OS updates, installing applications, or other activities performed to configure the VM image.

Publish Automated process that creates a new VM image version prepared for deployment to managed computers.

Deploy Mark a published VM image version “Current” or “Staged” so it can be downloaded by managed computers.

Install After VHD files are downloaded, Engine will install the VM image as a local VM.

Run The installed VM will run on Engine independently of Hyper-V or the Synchronizer.

Download When a VM image version is deployed to a computer, Engine will download the VHD files from Synchronizer.



Authoring

Authoring means starting a VM image in Synchronizer console for:•Installing or updating the operating system.•Installing, updating, or configuring applications.•Anything else done to get the VM image into the desired state for deployment.

Synchronizer uses the Hyper-V API to create and start a Hyper-V VM. Hyper-V Manager should show the VM running.

In Synchronizer console, select the VM image then click “Start”.

The console for the Hyper-V VM is available through the Synchronizer console. This only works in Microsoft Internet Explorer and requires an Active-X plugin to be installed.



VM Shutdown

• When authoring is complete, the VM must be shutdown before it can be published.

• Synchronizer uses the Hyper-V API to shutdown VMs, or to react to VM shutdown.

The VM can also be shutdown from the Synchronizer console.

Best practice is to shutdown the VM from within the VM console. Synchronizer will automatically detect the VM shutdown.

After VM shutdown, Synchronizer will delete the Hyper-V VM definition (but not VHD files). The Hyper-V VM is created on every start and deleted after every shutdown.



Publishing

• Publishing prepares a VM image for deployment to managed computers.• During publish, Synchronizer will start a Hyper-V VM to run through publish scripts.• The publish process is fully automated.• Synchronizer does not provide console access to the Hyper-V VM during publish.

Synchronizer will create and start a Hyper-V VM, but the VM console is not connected. The VM should be left alone to run the publish scripts.

In Synchronizer console, select the VM image then click Version/Publish.

When the publish process is complete, a new version of the VM image should appear which can be deployed to client computers.

Virtual Appliance Mode



Synchronizer Installation Methods

Native InstallationSynchronizer is installed directly on the Hyper-V host. Hyper-V has direct access to Synchronizer VHD files. One computer is used for both Hyper-V and Synchronizer services.

Hyper-VManager

SynchronizerService

VM Working Storage

VHD VHD VHD

Native Windows Server

Virtual Appliance InstallationSynchronizer is installed in a VM and connects to a native (non-virtualized) Windows Server for Hyper-V. Hyper-V has access to VHD files through a shared folder exported from the Synchronizer VM.

Synchronizer VM

SynchronizerService

Hyper-V Server

Hyper-VManager

Shared Folder

VM Working Storage

VHD VHD VHD



Synchronizer Share: Synchronizer View

When Synchronizer is installed in virtual appliance mode:

•The Synchronizer installation folder is shared. The share name is nxtopcenter for historical reasons.

•Folder and share permissions are configured to allow the Hyper-V host access to VHD files managed by Synchronizer.

•This is how VHD files are shared between Synchronizer and Hyper-V.



Synchronizer Share: Hyper-V View

• When a VM is started within the console, Synchronizer will create and start a new Hyper-V VM.

• Hyper-V VMs created by Synchronizer can be recognized by the VM name.

• The Hyper-V VM is configured to boot from a VHD file stored within the Synchronizer share (note the UNC path).

• This is how VHD files are shared between Synchronizer and Hyper-V.

• VHD files are never copied from Synchronizer to Hyper-V. All access is through the Synchronizer share.



Virtual Appliance Mode and Synchronizer Backups

• When Synchronizer is installed in Virtual Appliance mode:• All Synchronizer data is stored in the Synchronizer VM.

• Or in the Synchronizer MSSQL database, which might be hosted on a different server.• There is no Synchronizer data stored on the Hyper-V server.• From the Synchronizer point of view, there is no need to back up the Hyper-V server.

• But there may be other reasons to do so, if the Hyper-V server is used for purposes other than Synchronizer.

• Backing up the Synchronizer VM will protect all Synchronizer data.• Plus the Synchronizer MSSQL database, if it is hosted on a different server.

• Synchronizer treats the Hyper-V server as a transient resource that may be replaced quickly and easily with no backup/restore required.



Loss of Hyper-V Services

What Happens if the Hyper-V Server is Lost?•Synchronizer will be unable to start or publish VMs.•All other Synchronizer functionality should still work.•There is no possibility of data loss because all data is stored in the Synchronizer VM.•Previously published VM images can still be deployed from Synchronizer to Engine.•Managed computers and deployed VMs will continue running normally.

How To Recover from Loss of Hyper-V Services?•Resolve the Hyper-V server issue and bring it back online.

• Getting Hyper-V back up is important but usually not urgent since most Synchronizer functionality remains available without Hyper-V.

•If it is necessary to replace the Hyper-V server with a different computer:• Bring a new Windows server online with the Hyper-V role enabled.• Update Hyper-V Configuration in the Synchronizer console.• Enable Hyper-V privileges for the Hyper-V Integration Account.• Update the Hyper-V Appliance Local Administrators Group.• Reactivate the Virtual Appliance in the Synchronizer console.



Hyper-V in VMWare Environments

• Synchronizer may be installed in a VMWare VM, but Hyper-V is still needed for authoring and publishing of XCE VMs.

• Only the primary Synchronizer server uses Hyper-V. Remote Synchronizer servers may be installed in VMWare VMs with no Hyper-V integration.

• The Synchronizer VM and all Synchronizer data can be managed and protected using established mechanisms for VMWare VMs.

• If the Hyper-V server is lost, Synchronizer data is not affected. All Synchronizer functionality (besides authoring and publishing) remains available. VMs deployed to Engine are not affected at all.

• Nested virtualization (running Hyper-V within a VMWare VM) is untested and unsupported. It may work to some extent but nested Hyper-V VMs may suffer from poor performance.

VMWare Servers

XCE VM

C:

Hyper-V Server

Network Share

VHD Repository

Synchronizer VM

VHD VHD VHD

Preparing Hyper-V for Synchronizer



Preparing Hyper-V for Synchronizer

These steps should be completed before installing the primary Synchronizer server.•Identify the computer that will run Hyper-V.

• Native Hyper-V Integration:• This will be the same computer that Synchronizer will be installed on.

• Virtual Appliance Integration:• A computer with native (non-virtualized) Windows Server (2008-R2 or 2012).• Joined to the same Windows domain as the Synchronizer VM.• Good network connectivity to the Synchronizer VM.

•In the system BIOS, enable virtualization (Intel VT-x, AMD-V) and No-Execute (NX) CPU features.•Enable the Hyper-V role in Windows Server Manager.•Create a virtual network in Hyper-V manager.

• Best Practice: Name the virtual network “External Network”.• Make sure the virtual network is connected to the right network interface.

•Perform Hyper-V Functional Verification.•Identify or create a Windows user account for Hyper-V integration.

• Best Practice: Create a new Windows domain account specifically for Synchronizer integration with Hyper-V and Active Directory.

•Configure the account for Hyper-V access (see Hyper-V Integration Account).•Update the local administrators group on the Hyper-V server.



Hyper-V Integration Account

• Synchronizer needs a Windows user account for Hyper-V integration.• Account credentials are set during Synchronizer installation but can be changed later.• The type of account that may be used depends on the Synchronizer installation mode.

Native Installation• The local Administrator account is often used and should work by default.• A different local account, or a Windows domain account, may be used if desired.• But anything other than the local Administrator must be configured with proper permissions.• Simply being in the local Administrators group is usually insufficient.

Virtual Appliance Installation• A domain account must be used. Local accounts cannot be used.• The Hyper-V server and the Synchronizer VM must be joined to the same Windows domain.• The domain account must be configured with proper permissions.• Simply being in the local Administrators or Domain Admins group is usually insufficient.

Account Permissions Configuration• Choose one the following depending on the version of Hyper-V being used:

• Hyper-V Privileges: Windows Server 2008 R2• Hyper-V Privileges: Windows Server 2012



Hyper-V Server Local Administrators Group

• The local Administrators group on the Hyper-V server should include:

• The domain account used for Synchronizer/Hyper-V integration.

• The computer account for the VM running the primary Synchronizer server.

This is the local Administrators group on the Hyper-V appliance.

Computer account of the VM where the primary Synchronizer server is installed.

User account used to integrate Synchronizer with Hyper-V.



Hyper-V Privileges: Windows Server 2008 R2

• Login to the Hyper-V host server as a domain user (not a local user).

• Download the HVREMOTE script (hvremote.wsf) from Microsoft:

http://code.msdn.microsoft.com/windowsdesktop/Hyper-V-Remote-Management-26d127c6

• Open a command prompt (DOS box) with Administrator privileges.

• Navigate to the location of the HVREMOTE script and run the following command (substitute the correct domain short name and account name):

cscript hvremote.wsf /add:DOMAIN\account-name

• For example, if the domain short name is ORC and the account name is mswheel-admin:

cscript hvremote.wsf /add:ORC\mswheel-admin

• If successful, the script should display some messages like those shown below.

• If the Windows firewall isn’t enabled, the script may complain about it, but the operation should still succeed.



Hyper-V Privileges: Windows Server 2012

• Windows Server 2012 includes a new group Hyper-V Administrators.

• The Hyper-V integration account should be added to this group.

• Use the Computer Management application as shown below.

• Or run this command in a command prompt with Administrator privileges:

net localgroup “Hyper-V Administrators” /add DOMAIN\account-name

• For example, if the domain short name is ORC and the domain account is neon-admin:net localgroup “Hyper-V Administrators” /add ORC\neon-admin



Hyper-V Functional Verification

• Use this method to verify Hyper-V can boot a very basic VM.• To check Hyper-V before installing Synchronizer.• Or as a troubleshooting technique if Synchronizer is unable to start Hyper-V VMs.

• Create a new VM in Hyper-V manager. In the VM creation wizard:• VM Name and Location: Accept default settings.• Assign Memory: Accept default settings.• Configure Networking: Accept default settings.• Connect Virtual Hard Disk: Choose “Attach a Virtual Hard Disk Later”.

• Start the VM. It will start even without a virtual disk or boot device assigned.• If the VM goes into “Running” state then it is confirmed that Hyper-V is able to start VMs.• The VM can be deleted after a successful test.

Create a very basic VM with no virtual disk or boot device, then start it.

The VM should go to “Running” state, although the VM console will display a boot failure.

If the VM fails to start, it indicates a Hyper-V problem that should be resolved.

Hyper-V Configuration



Hyper-V Detection During Synchronizer Installation

• The Synchronizer installer checks for Hyper-V.

• If Hyper-V is found, Synchronizer is installed in Native mode.

• If Hyper-V is not found, Synchronizer is installed in Virtual Appliance mode.

• This message indicates Hyper-V was not found and Synchronizer will be installed in Virtual Appliance mode.

• If this is what you want, then proceed with the installation.

• But if you meant to install in Native mode, cancel the Synchronizer installation, enable Hyper-V, then restart the installer.

• Switching from Virtual Appliance to Native mode (or vice-versa) can’t be done within the Synchronizer console after Synchronizer is installed.

• The Hyper-V check is only done for the primary Synchronizer. Remote servers don’t use Hyper-V.



Hyper-V Configuration During Synchronizer Installation

Native Installation•A Hyper-V hostname is not necessary. Synchronizer will use Hyper-V services on the local Windows server.•The local Administrator account is often used, and should work by default.•A different account may be used, but account privileges must be configured to allow access to Hyper-V services.

Virtual Appliance Installation•A fully-qualified Hyper-V host name is required. Do not use an IP address.•A Windows domain account must be used. The domain short name prefix is required.•The domain account must be configured with privileges to use Hyper-V services on the Hyper-V host computer.

• Hyper-V integration configuration is set during Synchronizer installation.• Configuration properties can be changed later within Synchronizer console.



Hyper-V Configuration in Synchronizer Console

Hyper-V configuration is defined for the primary server in the Hyper-V tab.

Synchronizer will connect to the Hyper-V API using this hostname. It must be a fully-qualified hostname, not an IP address.

Virtual network for Hyper-V VMs created by Synchronizer. See Hyper-V Virtual Networks for details.

Port used by Synchronizer to connect to the Hyper-V console service. The default port is almost always correct.

Synchronizer uses these credentials for Hyper-V manager connections. The domain short-name prefix is required. See Hyper-V Credentials for details.



Virtual Appliance Configuration

• Virtual appliance configuration is defined for the primary Synchronizer server in the Virtual Appliance tab.

• This tab is not available for native installations (Synchronizer installed directly on the Hyper-V host server).

• The UNC paths are used by Hyper-V to access VHD and ISO files managed by Synchronizer.

• UNC paths are mostly for display purposes. It is very rare that they would ever need to be changed.

• If you think you need to change these paths, please contact XenClient Enterprise support for guidance.



Hyper-V Virtual Network

Synchronizer Hyper-V configuration includes a virtual network name.

Hyper-V VMs created by Synchronizer are configured to connect to the named virtual network.

The virtual network must match an entry in the Hyper-V virtual network manager.



Virtual Appliance Activation

• This action creates and configures the Synchronizer shared folder so Hyper-V can access VHD files managed by Synchronizer.

• Initial virtual appliance activation should be done automatically when Synchronizer is installed in virtual appliance mode.

• Do not reactivate the virtual appliance if any Hyper-V VMs are using VHD files in the Synchronizer shared folder!

• Reactivation deletes and recreates the folder share, which will disconnect the VHD file from the Hyper-V VM.

• This may result in the Hyper-V VM crashing and possibly also disk corruption.

To activate or reactivate the virtual appliance, select the primary server in the Overview section, then click the Activate Appliance action.



When to Reactivate the Virtual Appliance

• Virtual appliance reactivation deletes then recreates the Synchronizer shared folder.

• So the Hyper-V server can access VHD files managed by Synchronizer and stored within the shared folder.

• Virtual appliance reactivation is rare but may be necessary if:

• There is a significant change to the Hyper-V appliance computer (new hostname, Windows reinstall, domain unjoin/rejoin, etc.)

• Synchronizer needs to use a different computer for Hyper-V integration.

• The user account for Synchronizer/Hyper-V integration changes.

• Synchronizer is migrated to a different Windows server.

• The Synchronizer install folder, or the VmWorkingStorage subfolder, is moved to a different disk.

• The virtual appliance may also be reactivated as a troubleshooting technique if Synchronizer is unable to start Hyper-V VMs.

• Before reactivating the virtual appliance, make sure all VM images in Synchronizer are shut down.

Hyper-V Sharing



Hyper-V Sharing

• The Hyper-V server might be shared by multiple primary Synchronizer servers.

• The Hyper-V server and all Synchronizer servers must be joined to the same Windows domain.

• Each Synchronizer server can use the Hyper-V API independently with no need for coordination.

• The naming convention for Hyper-V VMs created by Synchronizer should avoid conflicts between multiple Synchronizer servers.

• But one Synchronizer could start many VMs and use up all the memory on the Hyper-V host, preventing another Synchronizer from starting a VM.



Hyper-V Sharing: Synchronizer Configuration

• Two different primary Synchronizer servers (mswheel and mstrash) are configured to use the same Hyper-V host.

• Neither server is aware of the other. The Hyper-V API and Synchronizer VM naming conventions provide all necessary coordination.



Hyper-V Sharing: Hyper-V Manager

• Multiple primary Synchronizer servers may be installed in different VMs on the same virtualization platform (Hyper-V in this case).

• Multiple primary Synchronizer servers may also integrate with the same Hyper-V host for authoring and publishing VMs.

• When a VM is started within Synchronizer console, Synchronizer uses the Hyper-V API to create and start a new Hyper-V VM. The VM definition will be deleted automatically after it is shut down.

• The naming convention for VMs created by Synchronizer is designed to avoid conflicts between VMs started by different Synchronizer servers.

The mstrash and mswheel Synchronizer servers are installed in these VMs.

This VM was created by Synchronizer mswheel when a Windows 7 VM was started within the mswheel console.

This VM was created by Synchronizer mstrash when a Windows 8 VM was started within the mstrash console.

Common Hyper-V Problems



Insufficient Memory

• This error means Hyper-V doesn’t have enough memory to start a VM.

• Usually caused by starting multiple VM images within Synchronizer console.

• Check for Synchronizer VM images that can be shut down to free up memory.

• Also check for VM images being published. The publish process starts Hyper-V VMs to run through a series of publish scripts.

• Check the Hyper-V manager for VMs that may have been started outside of Synchronizer.

• Check the VM image configuration in Synchronizer. Look for a memory setting that is unusually high.

• Additional memory may be added to the Hyper-V server to give more flexibility in starting multiple VM images in Synchronizer console.



Hyper-V Connection Failure

• This error means Synchronizer was unable to connect to the Hyper-V service.

• Check the Hyper-V configuration in Synchronizer console. Make sure the Hyper-V host is correct.

• On the Hyper-V server, make sure Hyper-V manager can start and connect to the Hyper-V host.

• Verify the Hyper-V server is online with good network connectivity between Hyper-V and the Synchronizer.

• Check for a firewall that may be blocking access to the Hyper-V service.



Hyper-V Authentication or Authorization Failure

• This error means a request from Synchronizer to the Hyper-V service failed.

• Most likely due to an authentication or permissions issue.

• In Hyper-V Configuration, make sure the correct user name and password are set.

• In Active Directory, make sure the user account isn’t disabled or has an expired password.

• Reset the password if necessary, then update Hyper-V Configuration in Synchronizer console.

• Verify Hyper-V privileges are configured correctly for the Hyper-V Integration Account.

• Verify configuration of the Hyper-V Appliance Local Administrators Group.

• Reactivate the virtual appliance in the Synchronizer console.



Virtual Network Not Found

• This error means Synchronizer tried to create a Hyper-V VM definition with a virtual network that doesn’t actually exist.

• Check the Hyper-V integration settings in Synchronizer console.

• The virtual network should match an actual virtual network defined in the Hyper-V manager.

• For more information see Hyper-V Virtual Network.



Synchronizer Shared Folder Permissions

• This error means Hyper-V was unable to access resources within the Synchronizer shared folder.

• Verify Hyper-V Configuration in Synchronizer console.

• Make sure the Synchronizer installation folder is shared, with full Read/Write permissions granted to the computer account of the Hyper-V server.

• Try reactivating the virtual appliance in Synchronizer console.

• Check for a local or domain security setting (GPO) that might be blocking access to the shared folder.



Hypervisor Not Running

• This error means Hyper-V could not start a VM because the hypervisor is not running.

• Perform Hyper-V Functional Verification.

• Verify the following CPU features are enabled in the system BIOS for the Hyper-V server:

• Virtualization technology (Intel VT-x or AMD-V).

• No Execute (NX) flag, which may be identified as a “Memory Protection” or “Virus Protection” feature on some systems.

• If the problem persists after enabling virtualization technology in the BIOS, the following steps are recommended:

1. Complete power-down of the Hyper-V server.

2. Disconnect the computer from the power supply.

3. Wait one minute then reconnect the power supply and power-up the computer.

Documents

June 10, 2013 XenClient Enterprise 5.0 Synchronizer and Hyper-V