Creating a VMkernel connection to optimize ESXi storage traffic

By configuring a VMkernel connection, you can place ESXi storage traffic and user-related traffic on separate networks, and congestion problems will be a thing of the past.

VMware ESXi storage traffic places a great strain on a network, which can hurt virtual machine (VM) performance during periods of network congestion. By setting up a separate VMkernel network connection for ESXi storage traffic, you can improve network performance across the entire infrastructure.

ESXi uses two types of network connections:

  1. Virtual machine: handles VM network traffic and can separate traffic between VMs -- which can improve network performance. And if you separate traffic on a different network, you can also improve network bandwidth.
  2. VMkernel: This TCP/IP stack controls VMware specific services, such as vMotion, iSCSI and Network File System (NFS) storage traffic, or network connections for host management.

By default, all traffic is configured for one network interface. But it's good idea to set up a new VMkernel connection on a different network -- especially if you use iSCSI- or NFS-based storage, which are traffic-intensive protocols.

If you have a dedicated network infrastructure to support iSCSI packages, for example, you can use the vSphere Client to create a VMkernel interface to optimize ESXi storage traffic.

Setting up a VMkernel connection for ESXi storage traffic
With a dedicated storage network in place, you can use follow these steps to add a VMkernel interface to separate ESXi storage and VM traffic.

In the vSphere Client, connect to the host that you want to configure and click the Configuration tab. Next, click the Add Networking link in the upper-right corner of the tab.

In the Add Network wizard, select a connection and choose the VMkernel option.

Figure 1
Select the VMkernel network type to create a dedicated ESXi storage interface. (Click image for an enlarged view.)

The next interface provides two options: create a virtual switch or use vSwitch0 (or any other switch that is already configured).

From this interface, it makes sense to create a virtual switch for ESXi storage traffic. It's also good idea to assign more than one network card to the new virtual switch, which doubles its available bandwidth and offers redundancy. Don't forget to look at the Preview window to review the configuration changes.

Figure 2
For a dedicated ESXi storage network, create a new virtual switch and add at least two network cards to the switch. (Click image for an enlarged view.)

Next, you need to specify some port-group properties, such as a network label, an optional virtual LAN (VLAN) ID and a specification for the interface. If this interface will handle only storage traffic, you don't have to specify anything. (If it's for vMotion, Fault Tolerance logging or management traffic, select the corresponding option.)

Figure 3
Assign the new port to a VLAN and specify what you will use it for. (Click image for an enlarged view.)

At this point, configure an IP address for the new interface. If you are configuring an ESXi storage network interface, the IP address should be different from the IP address that's used for the management interface.

Clicking Next adds the new interface to the configuration overview and you should be able to start using the new storage network.

This was first published in April 2011

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