Paravirtualization Process

There are several tasks you must perform to switch from HVM to PVM.

The following figure shows the overall task flow.

HVM to PVM Conversion Task Flow

The installed Appliance comes with the Appliance Paravirtualization Support Tool, which is equipped with the following:

  • Displays the current paravirtualization status of the appliance.
  • Displays Next Boot paravirtualization status of the appliance.
  • Converts from HVM to PVM and back again.
  • Connects to the XenServer and configures the Xen hypervisor for HVM or PVM.

Starting the Appliance Paravirtualization Support Tool

You can use Appliance Paravirtualization Support Tool to configure the local appliance for PVM.

To start the Appliance Paravirtualization Support Tool:

  1. Access the ESA CLI Manager.

  2. Navigate to Tools > Xen ParaVirtualization screen.

    The root permission is required for entering the tool menu.

    When you launch the tool, the main screen shows the current system status and provides options for managing virtualization.

    Appliance Paravirtualization Support Tool Main Screen

Enabling Paravirtualization

When you convert your appliance to PVM mode, the internal configuration is modified and the Next Boot status changes to support paravirtualization. Both virtual block device and virtual console support is enabled as well.

To enable Paravirtualization:

  1. To enable PVM on the appliance, you need to configure both XenServer and the appliance.

    You can configure XenServer in two ways:

    • Copy the tool to the XenServer and execute it locally, not using the appliance.
    • Execute the commands manually using the xe command of Xen console.
  2. To configure the local appliance for PVM from the Appliance Paravirtualization Support Tool main screen, select Enable paravirtualization settings.

The status indicators in the Next boot configuration section of the main screen change from Disabled to Enabled.

Configuring Host for PVM

To configure the Host for PVM, you need to have access to the XenServer machine.

Once the local Appliance is configured to use PVM, you connect to the XenServer to run the Xen ParaVirtualization Support Tool. This configures changes on the Xen hypervisor so that it runs in Host PVM mode. You will be asked for a root password upon launching the tool.

The following figure shows the main screen of the Xen Paravirtualization Support Tool.

Xen ParaVirtualization Support Tool Main Screen

To configure the Host for PVM:

  1. From the Appliance ParaVirtualization Support Tool main screen, select Connect to XenServer hypervisor and execute tool.

  2. Select OK.

    The XenServer hypervisor interface appears.

  3. At the prompt, type the IP or host name of the XenServer.

  4. Press ENTER.

  5. At the prompt, type the user name for SCP/SSH connection.

  6. Press ENTER.

  7. At the prompt, type the password to upload the file.

  8. Press ENTER.

    The tool is uploaded to the /tmp directory.

  9. At the prompt, type the password to remotely run the tool.

  10. Press ENTER.

    An introduction message appears.

  11. At the prompt, type the name of the target virtual machine.

    Alternatively, press ENTER to list available virtual machines.

    The Xen ParaVirtualization Support Tool Main Screen appears and shows the current virtual machine information and status.

  12. Type 4 to enable paravirtualization settings.

  13. Press ENTER.

    The following screen appears.

    Xen ParaVirtualization Settings Screen

  14. At the prompt, type Y to save the configuration.

  15. Press ENTER.

  16. You can use option 3 to back up the entries that will be modified.
    The backup is stored in the /tmp directory on the XenServer machine as a rollback script that can be executed later on to revert the configuration back from PVM to HVM.

  17. Type q to exit the Appliance Paravirtualization Support Tool.

Rebooting the Appliance for PVM

After configuring the appliance and the Host for PVM, the appliance must be restarted. When it restarts, it will come up and run in PVM mode.

Before you begin

Before rebooting the appliance:

  • Exit both local and remote Paravirtualization tools before rebooting the appliance.

  • In the PVM, the system might not boot if there are two bootable devices. Be sure to eject any bootable CD/DVD on the guest machine.

  • If you encounter console issues after reboot, then close the XenCenter and restart a new session.

Booting into System Restore mode

You cannot boot in the System Restore mode when in the Xen Server PVM mode, because it does not show up during appliance launching and appears only if you have previously backed up the OS. However, you can boot in the System Restore mode when in the Xen Server HVM mode.

How to reboot the appliance for PVM

To reboot appliance for PVM:

  1. To reboot the appliance for PVM, navigate to Administration > Reboot and Shutdown > Reboot.

  2. Restart the Appliance Paravirtualization Support Tool and check the main screen to verify the current mode.

Disabling Paravirtualization

To disable Paravirtualization:

  1. To revert the appliance back to HVM, you need to disable paravirtualization on the guest appliance OS and on the XenServer.

  2. To return the appliance to HVM, use the Disable Paravirtualization Settings option, available in the Appliance Paravirtualization Support Tool.

    The status indicators in the Next boot configuration section on the main screen change from Enabled to Disabled.

  3. To return the XenServer to HVM, perform one of the following tasks to revert the XenServer configuration to HVM:

    If…Then…
    You backed up the XenServer configuration by creating a rollback script while switching from HVM to PVM, using option 3 on the Xen Paravirtualization Support ToolExecute the rollback script.
    You want to use the Xen Paravirtualization Support ToolUse the Xen Paravirtualization Support Tool to connect to the XenServer, and then type 5 to select Disable paravirtualization Setting (enable HVM). For more information about connecting to the XenServer, refer to section Configure Host for PVM.
    You want to perform a manual conversionManually convert from PVM to HVM. For more information about converting from PVM to HVM, refer to section Manual Configuration of Xen Server.