How To Configure VMDirectPath HBA in vSphere

On the rare instance you'll need exclusive access to a PCI device, you can isolate it via VMDirectPath HBA.

There are so many vSphere features that are new, it's sometimes difficult to keep up with the ones that have been there that are still useful. One such feature is VMDirectPath HBA, which allows a VMware VM to have exclusive access to a PCI device.

VMDirectPath HBA can be beneficial for putting individual storage systems on a storage network or to a fully separated device for a number of reasons. Though rare, there are use cases where you might need to do this. The most frequent is a storage management console for Fibre Channel networks. This setting is administered in the advanced hardware settings of an ESXi host (see Fig. 1).

Available PCI devices on a supported host can be assigned for passthrough.
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Figure 1. Available PCI devices on a supported host can be assigned for passthrough.

Once a PCI device is available for passthrough, the individual device is selected among all possible devices. If you go to this step, be very careful to select the right devices to be presented to an individual VM (see Fig. 2).

Every available device has its own PCI identification in the vSphere Client.
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Figure 2. Every available device has its own PCI identification in the vSphere Client.

As a primer, be sure to read VMware KB 1010789 for more information. There are a number of configuration requirements in the KB that need to be in place for passthrough to work. Additionally, it's important to note that this removes the PCI device from the ESXi host's access to the hardware.

Once a VM has this PCI device added, the direct enumeration in the guest virtual machine will allow access to the device. There may be a driver required, depending on the PCI device and the operating system involved. This is something that VMware Tools doesn't help with as they are not the synthesized drivers that the VM is using for everything else.

Have you tried using VMDirectPath HBA? If so, what for? Share your comments here.

About the Author

Rick Vanover (Cisco Champion, Microsoft MVP, VMware vExpert) is based in Columbus, Ohio. Vanover's experience includes systems administration and IT management, with virtualization, cloud and storage technologies being the central theme of his career recently. Follow him on Twitter @RickVanover.

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