ESX Configuration Guide

VMDirectPath I/O

VMDirectPath I/O allows virtual machine access to physical PCI functions on platforms with an I/O Memory Management Unit.

The following features are unavailable for virtual machines configured with VMDirectPath:

nvMotion

nHot adding and removing of virtual devices

nSuspend and resume

nRecord and replay

nFault tolerance

nHigh availability

nDRS (limited availability. The virtual machine can be part of a cluster, but cannot migrate across hosts)

Configure Passthrough Devices on a Host

You can configure passthrough networking devices on a host.

Procedure

1 Select a host from the inventory panel of the vSphere Client.

2On the Configuration tab, click Advanced Settings.

The Passthrough Configuration page appears, listing all available passthrough 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.

3Click Edit.

4Select the devices to be used for passthrough and click OK.

Configure a PCI Device on a Virtual Machine

You can configure a passthrough PCI device on a virtual machine.

Procedure

1 Select a virtual machine from the inventory panel of the vSphere Client. 2 From the Inventory menu, select Virtual Machine > Edit Settings.

3 On the Hardware tab, click Add.

4Select PCI Device and click Next.

5 Select the passthrough device to use, and click Next.

6Click Finish.

Adding a VMDirectPath device to a virtual machine sets memory reservation to the memory size of the virtual machine.

The following best practices, configuration scenarios, and troubleshooting guidelines provide suggestions for common networking configurations and pitfalls.

This chapter includes the following topics:

n“Networking Best Practices,” on page 67

n“Mounting NFS Volumes,” on page 68

n“Networking Configuration for Software iSCSI and Dependent Hardware iSCSI,” on page 68

n“Configuring Networking on Blade Servers,” on page 72

n“Troubleshooting,” on page 74

Networking Best Practices

Consider these best practices for configuring your network.

nSeparate network services from one another to achieve greater security or better performance.

To have a particular set of virtual machines function at the highest performance levels, put them on a separate physical NIC. This separation allows for a portion of the total networking workload to be more evenly shared across multiple CPUs. The isolated virtual machines can then better serve traffic from a Web client, for instance.

nYou can satisfy the following recommendations either by using VLANs to segment a single physical network or separate physical networks (the latter is preferable).

n Keeping the service console on its own network is an important part of securing the ESX system. Consider the service console network connectivity in the same light as any remote access device in a host, because compromising the service console gives an attacker full control of all virtual machines running on the system.

n Keeping the vMotion connection on a separate network devoted to vMotion is important because when migration with vMotion occurs, the contents of the guest operating system’s memory is transmitted over the network.

nWhen using passthrough devices with a Linux kernel version 2.6.20 or earlier, avoid MSI and MSI-X modes because these modes have significant performance impact.

nTo physically separate network services and to dedicate a particular set of NICs to a specific network service, create a vSwitch for each service. If this is not possible, separate them on a single vSwitch by attaching them to port groups with different VLAN IDs. In either case, confirm with your network administrator that the networks or VLANs you choose are isolated in the rest of your environment and that no routers connect them.