Hyper-V: The number of virtual processors in use must not exceed the supported maximum

Updated: April 27, 2010

Applies To: Windows Server 2008 R2

This topic is intended to address a specific issue identified by a Best Practices Analyzer scan. You should apply the information in this topic only to computers that have had the Hyper-V Best Practices Analyzer run against them and are experiencing the issue addressed by this topic. For more information about best practices and scans, see Best Practices Analyzer.


Operating System

Windows Server 2008 R2







Too many virtual processors are running.

Microsoft does not support the number of virtual processors that are running.

Reduce the number of running virtual processors by moving virtual machines to another server or reducing the number of total virtual processors assigned to all running virtual machines.

To move a virtual machine to another server, you can export the virtual machine from the current server and then import it to a new server as described in the following procedures. Or, if this server belongs to a failover cluster, use the tools provided with the failover clustering feature to move the virtual machines. For instructions about moving a virtual machine, see Live Migrate, Quick Migrate, or Move a Virtual Machine from Node to Node (http://go.microsoft.com/fwlink/?LinkID=181519).

To reduce the number of running processors without moving virtual machines, you can either modify the settings of some of the virtual machines as described in the following procedure, or stop running any virtual machines that do not have to be running.

By default, membership in the local Administrators group, or equivalent, is the minimum required to complete these procedures, except where noted. However, an administrator can use Authorization Manager to modify the authorization policy so that a user or group of users can complete this procedure. For more information, see Using Authorization Manager for Hyper-V Security (http://go.microsoft.com/fwlink/?LinkId=142886).

  1. Open Hyper-V Manager. Click Start, point to Administrative Tools, and then click Hyper-V Manager.

  2. In the results pane, under Virtual Machines, right-click a virtual machine and then click Export.

  3. In the Export a Virtual Machine dialog box, type or browse to a location that has enough free space to store all of the virtual machine resources. When you export a virtual machine, all virtual hard disks (.vhd files), snapshots (.avhd files), and saved state files associated with the virtual machine are copied to the specified folder.

    In a domain environment, if you specify a remote location such as a shared network folder or a folder on the server you want to import the virtual machine to, you must configure the server running Hyper-V for constrained delegation. You need to do this so that the computer account of the server running Hyper-V can present delegated credentials for the Common Internet File System (CIFS) service type. For instructions, see the following procedure.

  4. Click Export.

If you need to configure constrained delegation, complete the following procedure and then export the virtual machines. By default, membership in the Domain Administrators group is required to complete this procedure.

  1. On a computer that has the Active Directory Domain Services Tools feature installed, in Administrative Tools, open Active Directory Users and Computers, and then navigate to the computer account for the computer running Hyper-V.

    If Active Directory Users and Computers is not listed, install the Active Directory Domain Services Tools feature. For instructions, see Installing Remote Server Administration Tools for AD DS (http://go.microsoft.com/fwlink/?LinkId=140463).

  2. Right-click the computer account for the computer running Hyper-V, and then click Properties.

  3. On the Delegation tab, click Select this computer for delegation to specified services only, and then click Use any authentication protocol.

  4. To allow the Hyper-V computer account to present delegated credentials to the remote computer:

    1. Click Add.

    2. In the Add Services dialog box, click Users or Computers, select the remote computer, and then click OK.

    3. In the Available services list, select the cifs protocol (also known as the Server Message Block (SMB) protocol), and then click Add.

After exporting the virtual machines, import the virtual machines to the other server.

  1. Connect to the server running Hyper-V and open Hyper-V Manager.

  2. In the Action pane, click Import Virtual Machine.

  3. In the Import Virtual Machine dialog box, specify the location where you exported the virtual machine. Unless you want to reimport this virtual machine, leave the import settings as they are.

  4. Click Import.

If you want to reduce the number of running virtual processors by removing processors from some of the virtual machines, perform the following procedure.

  1. Open Hyper-V Manager. Click Start, point to Administrative Tools, and then click Hyper-V Manager.

  2. In the results pane, under Virtual Machines, select the virtual machine that you want to configure. The state of the virtual machine should be listed as Off. If it is not, right-click the virtual machine and then click Shut Down.

  3. In the Action pane, under the virtual machine name, click Settings.

  4. In the navigation pane, click Processor.

  5. On the Processor page, reduce the number of processors and then click OK.

For more information about supported configurations of Hyper-V and virtual machines running with Hyper-V, see Requirements and Limits for Virtual Machines and Hyper-V in Windows Server 2008 R2 (http://go.microsoft.com/fwlink/?LinkID=180919).

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