6.5.1

In addition to the previous restrictions, the following types of IPv6 address types are not supported for use
with the vSphere HA isolation address or management network: link-local, ORCHID, and link-local with
zone indices. Also, the loopback address type cannot be used for the management network.
N To upgrade an existing IPv4 deployment to IPv6, you must rst disable vSphere HA.
Creating a vSphere HA Cluster
vSphere HA operates in the context of a cluster of ESXi (or legacy ESX) hosts. You must create a cluster,
populate it with hosts, and congure vSphere HA seings before failover protection can be established.
When you create a vSphere HA cluster, you must congure a number of seings that determine how the
feature works. Before you do this, identify your cluster's nodes. These nodes are the ESXi hosts that will
provide the resources to support virtual machines and that vSphere HA will use for failover protection. You
should then determine how those nodes are to be connected to one another and to the shared storage where
your virtual machine data resides. After that networking architecture is in place, you can add the hosts to
the cluster and nish conguring vSphere HA.
You can enable and congure vSphere HA before you add host nodes to the cluster. However, until the hosts
are added, your cluster is not fully operational and some of the cluster seings are unavailable. For example,
the Specify a Failover Host admission control policy is unavailable until there is a host that can be
designated as the failover host.
N The Virtual Machine Startup and Shutdown (automatic startup) feature is disabled for all virtual
machines residing on hosts that are in (or moved into) a vSphere HA cluster. Automatic startup is not
supported when used with vSphere HA.
vSphere HA Checklist
The vSphere HA checklist contains requirements that you must be aware of before creating and using a
vSphere HA cluster.
Review this list before you set up a vSphere HA cluster. For more information, follow the appropriate cross
reference.
n
All hosts must be licensed for vSphere HA.
n
A cluster must contain at least two hosts.
n
All hosts must be congured with static IP addresses. If you are using DHCP, you must ensure that the
address for each host persists across reboots.
n
All hosts must have at least one management network in common. The best practice is to have at least
two management networks in common. You should use the VMkernel network with the Management
 checkbox enabled. The networks must be accessible to each other and vCenter Server and the
hosts must be accessible to each other on the management networks. See“Best Practices for
Networking,” on page 38.
n
To ensure that any virtual machine can run on any host in the cluster, all hosts must 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.
N vSphere HA uses datastore heartbeating to distinguish between partitioned, isolated, and failed
hosts. So if some datastores are more reliable in your environment, congure vSphere HA to give
preference to them.
n
For VM Monitoring to work, VMware tools must be installed. See “VM and Application Monitoring,”
on page 15.
Chapter 2 Creating and Using vSphere HA Clusters
VMware, Inc. 27