Review or Adjust the Network That is Used for MPI Messages in an HPC Cluster

  • Article

Applies To: Windows HPC Server 2008

In Windows HPC Server 2008, if a cluster is used to run Message Passing Interface (MPI) jobs, MPI messages will by default be passed on the private or application network, and not on the enterprise network. This is the more secure configuration, and is relevant because of the way MPI messages are handled. However, the environment variable that controls this might have been changed by an administrator (after being set automatically by Windows HPC Server 2008 during installation).

The following procedure describes methods for viewing the environment variable, and for ensuring that it specifies an appropriate network mask for MPI messages. For more information about private, application, and enterprise networks in an HPC cluster, and how MPI messages are passed on those networks, see "Considerations for an HPC cluster that will run MPI jobs" in Understanding Security Considerations for Network Topologies in Windows HPC Server 2008.

To review or adjust the network that is used for MPI messages in an HPC cluster

  • Using HPC PowerShell

  • Using a command prompt window

To review or adjust the network that is used for MPI messages in an HPC cluster by using HPC PowerShell

  1. Click Start, point to All Programs, and then click Microsoft HPC Pack.

  2. Start HPC PowerShell:

    • If you are on a head node, right-click HPC PowerShell, and then click Run as administrator. If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Continue.

    • If you are on a client computer, click HPC PowerShell.

  3. If you are prompted by HPC PowerShell to choose if you want to run the ccppsh.format.ps1xml script, type A, and then press ENTER.

  4. Type:

    Get-HpcClusterProperty -Environment

  5. In the displayed results, opposite CCP_MPI_NETMASK, find the network mask specified in the first part of the environment variable, before the slash. This network mask uses 0 as a wildcard. For example, a value of 10.1.0.0 in the network mask represents the range 10.1.0.0 through 10.1.255.255.

  6. If the network mask does not specify the IP address range for the private or application networks only (and instead specifies or includes the IP address range for the enterprise network), adjust the mask by typing the following command:

    Set-HpcClusterProperty -Environment CCP_MPI_NETMASK=<CorrectAddressRange>/<SubnetMask>

    Where <CorrectAddressRange> is a network mask that uses 0 as a wildcard and represents the IP address range for the private network, application network, or both, and <SubnetMask> is the corresponding subnet mask, preceded by a forward slash.

Additional considerations

  • You cannot use the HPC Cluster Manager snap-in to review or adjust the network that is used for MPI messages in an HPC cluster. You must use either an HPC PowerShell cmdlet or a command at a command prompt window to perform this action.

Additional references

To review or adjust the network that is used for MPI messages in an HPC cluster by using a command prompt window

  1. To open a command prompt window as an administrator, click Start, right-click Command Prompt, and then click Run as administrator .

  2. If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Continue.

  3. Type:

    cluscfg  listenvs

  4. In the displayed results, opposite CCP_MPI_NETMASK, find the network mask specified in the first part of the environment variable, before the slash. This network mask uses 0 as a wildcard. For example, a value of 10.1.0.0 in the network mask represents the range 10.1.0.0 through 10.1.255.255.

  5. If the network mask does not specify the IP address range for the private or application networks only (and instead specifies or includes the IP address range for the enterprise network), adjust the mask by typing the following command:

    cluscfg  setenvs CCP_MPI_NETMASK=<CorrectAddressRange>/<SubnetMask>

    Where <CorrectAddressRange> is a network mask that uses 0 as a wildcard and represents the IP address range for the private network, application network, or both, and <SubnetMask> is the corresponding subnet mask, preceded by a forward slash.

Additional considerations

  • You cannot use the HPC Cluster Manager snap-in to review or adjust the network that is used for MPI messages in an HPC cluster. You must use either an HPC PowerShell cmdlet or a command at a command prompt window to perform this action.

Additional references