The vSphere HA checklist contains requirements that you need to be aware of before creating and using a vSphere HA cluster.

Review this list before setting up a vSphere HA cluster. For more information, follow the appropriate cross reference or see Creating a vSphere HA Cluster.

All hosts must be licensed for vSphere HA.


ESX/ESXi 3.5 hosts are supported by vSphere HA but must include a patch to address an issue involving file locks. For ESX 3.5 hosts, you must apply the patch ESX350-201012401-SG, while for ESXi 3.5 you must apply the patch ESXe350-201012401-I-BG. Prerequisite patches need to be applied before applying these patches.

You need at least two hosts in the cluster.

All hosts need to be configured with static IP addresses. If you are using DHCP, you must ensure that the address for each host persists across reboots.

There should be at least one management network in common among all hosts and best practice is to have at least two. Management networks differ depending on the version of host you are using.

ESX hosts - service console network.

ESXi hosts earlier than version 4.0 - VMkernel network.

ESXi hosts version 4.0 and later ESXi hosts - VMkernel network with the Management Network checkbox enabled.

See Best Practices for Networking.

To ensure that any virtual machine can run on any host in the cluster, all hosts should have access to the same virtual machine networks and datastores. Similarly, virtual machines must be located on shared, not local, storage otherwise they cannot be failed over in the case of a host failure.


vSphere HA uses datastore heartbeating to distinguish between partitioned, isolated, and failed hosts. Accordingly, you must ensure that datastores reserved for vSphere HA are readily available at all times.

For VM Monitoring to work, VMware tools must be installed. See VM and Application Monitoring.

Host certificate checking should be enabled. See Enable Host Certificate Checking.

vSphere HA supports both IPv4 and IPv6. A cluster that mixes the use of both of these protocol versions, however, is more likely to result in a network partition.