Saturday, March 27, 2010

VMDirectPath (ESX 4 Onwards it's mostly on GUI --> Configuration Examples and Troubleshooting

Now working with Tape Drives, Libraries & 10Gbps devices,
direct from VM's (not from ESX) is piece of cake..

VMware made it more easier through GUI - you don't need to make your hands dirty by editing .VMX.

However, be prepared for few special cases - need to edit .VMX again.

Configuring VMDirectPath I/O pass-through devices on an ESX host - Extract from VMware KB - 1010789 - Click this for link


This article provides steps for configuring VMDirectPath I/O direct PCI device connections for virtual machines running on Intel Weybridge and Stoakley platforms.


About VMDirectPath I/O pass-through devices

You can connect up to two passthrough devices to a virtual machine. When selecting the devices, keep in mind these restrictions:
  • Devices cannot be plugged in after a PCI Bridge.

  • You cannot have two devices in two different contexts (for example, one used by VMkernel and one in pass-through) using the same PCI slot. For example, the dual head NIC is dedicated to the VMkernel OR is available for pass-through. If you select one, the other is automatically selected as well. A dialog informs you why this occurred.

Configuring pass-through devices

To configure pass-through devices on an ESX host:
  1. Select an ESX host from the Inventory panel of VMware Infrastructure (VI) Client.
  2. On the Configuration tab, click Advanced SettingsThe Pass-through Configuration page lists all available pass-through devices.

    A green icon indicates that a device is enabled and active. An orange icon indicates that the state of the device has changed and the host must be rebooted before the device can be used.

  3. Click Edit.
  4. Select the devices and click OK.

    If you have a chipset with VT-d, when you click Advanced Settings in VI Client, you can select what devices are dedicated to the VMDirectPath I/O.
  5. When the devices are selected, they are marked with an orange icon. Reboot for the change to take effect. After rebooting, the devices are marked with a green icon and are enabled.

    Note: The configuration changes are saved in the /etc/vmware/esx.conf file. The parent PCI bridge, and if two devices are under the same PCI bridge, only one entry is recorded.
    The PCI slot number where the device was connected is 00:0b:0. It is recorded as:

    /device/000:11.0/owner = "passthru"

    0b is 11 in decimal.
To configure a PCI device on a virtual machine:
  1. From the Inventory in VI Client, right-click the virtual machine and choose Edit Settings.
  2. Click the Hardware tab.
  3. Click Add.
  4. Choose the PCI Device.
  5. Click Next.

    When the device is assigned, the virtual machine must have a memory reservation for the full configured memory size.

Additional Information

For related information, see the VMDirectPath Tech Note at

1 comment:

  1. This is a wonderful feature in ESX4 enabling the guests to handle SCSI, SAS or FC related devices to directly attach to the Guest OS.

    It is in fact much easier to configure in ESX4 compared to ESX3.5...


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