6.0

Other Configuration Recommendations
You should also observe the following guidelines when configuring Fault Tolerance.
n
If you are using NFS to access shared storage, use dedicated NAS hardware with at least a 1Gbit NIC to
obtain the network performance required for Fault Tolerance to work properly.
n
The memory reservation of a fault tolerant virtual machine is set to the VM's memory size when Fault
Tolerance is turned on. Ensure that a resource pool containing fault tolerant VMs has memory resources
above the memory size of the virtual machines. Without this excess in the resource pool, there might
not be any memory available to use as overhead memory.
n
Use a maximum of 16 virtual disks per fault tolerant virtual machine.
n
To ensure redundancy and maximum Fault Tolerance protection, you should have a minimum of three
hosts in the cluster. In a failover situation, this provides a host that can accommodate the new
Secondary VM that is created.
Preparing Your Cluster and Hosts for Fault Tolerance
To enable vSphere Fault Tolerance for your cluster, you must meet the feature's prerequisites and you must
perform certain configuration steps on your hosts. After those steps are accomplished and your cluster has
been created, you can also check that your configuration complies with the requirements for enabling Fault
Tolerance.
The tasks you should complete before attempting to enable Fault Tolerance for your cluster include the
following:
n
Ensure that your cluster, hosts, and virtual machines meet the requirements outlined in the Fault
Tolerance checklist.
n
Configure networking for each host.
n
Create the vSphere HA cluster, add hosts, and check compliance.
After your cluster and hosts are prepared for Fault Tolerance, you are ready to turn on Fault Tolerance for
your virtual machines. See “Turn On Fault Tolerance for Virtual Machines in the vSphere Client,” on
page 396.
Configure Networking for Host Machines in the vSphere Client
On each host that you want to add to a vSphere HA cluster, you must configure two different networking
switches so that the host can also support vSphere Fault Tolerance.
To enable Fault Tolerance for a host, you must complete this procedure twice, once for each port group
option to ensure that sufficient bandwidth is available for Fault Tolerance logging. Select one option, finish
this procedure, and repeat the procedure a second time, selecting the other port group option.
Prerequisites
Multiple gigabit Network Interface Cards (NICs) are required. For each host supporting Fault Tolerance,
you need a minimum of two physical gigabit NICs. For example, you need one dedicated to Fault Tolerance
logging and one dedicated to vMotion. Use three or more NICs to ensure availability.
NOTE The vMotion and FT logging NICs must be on different subnets and IPv6 is not supported on the FT
logging NIC.
Procedure
1 Log in to the vSphere Client and select a host in the inventory pane.
Chapter 27 Providing Fault Tolerance for Virtual Machines
VMware, Inc. 393