vSphere HA Interoperability with VSAN.

With the adoption of VSAN in vSphere infrastructure, we will be seeing a lot customers using VSAN as a HA shared storage.

Before configuring vSphere HA, you should be aware of the limitations of its interoperability with Virtual SAN.

To use vSphere HA with Virtual SAN, you must be aware of certain considerations and limitations for the

Interoperability of these two features.

ESXi Host Requirements

To use Virtual SAN with a vSphere HA cluster following prerequisites needs to be in place:

  • The cluster’s ESXi hosts all must be version 5.5 or later.
  • The cluster must have a minimum of three ESXi hosts.(basically it’s a VSAN requirement)

Understanding the Networking Differences:

Virtual SAN has its own dedicated network, VMware recommends to use a dedicated NIC with VSAN. When Virtual SAN and vSphere HA are enabled for the same cluster, the HA traffic flows over VSAN network rather than the management network. The management network is used by vSphere HA only when Virtual SAN is disabled.

It’s very important to note that “Virtual SAN can only be enabled when vSphere HA is disabled”.

If you change the Virtual SAN network configuration, the vSphere HA agents do not automatically pick up the new network settings. So to make changes to the Virtual SAN network, you must take the following

Steps in the vSphere Web Client:

1 Disable Host monitoring for the vSphere HA cluster.

2 Make the Virtual SAN network changes.

3 Right-click all hosts in the cluster and select Reconfigure for vSphere HA.

4 Re-enable Host monitoring for the vSphere HA cluster.

Below table shows the differences in vSphere HA networking when Virtual SAN is used or not.

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