Primary and Secondary
Hosts
You can add a secondary host to a cluster by
calling the
ClusterComputeResource.AddHost_Task
method,
which requires that you specify the host name, port, and password for the host
to be added as a
HostConnectSpec
.
When you add a host to a VMware HA cluster, an
agent is uploaded to the host and configured to communicate with other agents
in the cluster. The first five hosts added to the cluster are designated as
primary hosts, and all subsequent hosts are designated as secondary hosts. The
primary hosts maintain and replicate all cluster state and are used to initiate
failover actions. If a primary host is removed from the cluster, VMware HA
promotes another host to primary status.
Any host that joins the cluster must communicate
with an existing primary host to complete its configuration (except when you
are adding the first host to the cluster). At least one primary host must be
functional for VMware HA to operate correctly. If all primary hosts are
unavailable (not responding), no hosts can be successfully configured for
VMware HA.
One of the primary hosts is also designated as the
active primary host and its responsibilities include:
- Deciding where to restart virtual machines
- Keeping track of failed restart attempts
- Determining when it is appropriate to keep trying to restart a virtual machine.