6.7

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Use deterministic teaming policies to ensure particular traffic types have an affinity to a particular NIC
(active/standby) or set of NICs (for example, originating virtual port-id).
n
Where active/standby policies are used, pair traffic types to minimize impact in a failover situation
where both traffic types will share a vmnic.
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Where active/standby policies are used, configure all the active adapters for a particular traffic type
(for example, FT Logging) to the same physical switch. This minimizes the number of network hops
and lessens the possibility of oversubscribing the switch to switch links.
Note FT logging traffic between Primary and Secondary VMs is unencrypted and contains guest network
and storage I/O data, as well as the memory contents of the guest operating system. This traffic can
include sensitive data such as passwords in plaintext. To avoid such data being divulged, ensure that this
network is secured, especially to avoid 'man-in-the-middle' attacks. For example, you could use a private
network for FT logging traffic.
Homogeneous Clusters
vSphere Fault Tolerance can function in clusters with nonuniform hosts, but it works best in clusters with
compatible nodes. When constructing your cluster, all hosts should have the following configuration:
n
Common access to datastores used by the virtual machines.
n
The same virtual machine network configuration.
n
The same BIOS settings (power management and hyperthreading) for all hosts.
Run Check Compliance to identify incompatibilities and to correct them.
Performance
To increase the bandwidth available for the logging traffic between Primary and Secondary VMs use a
10Gbit NIC, and enable the use of jumbo frames.
You can select multiple NICs for the FT logging network. By selecting multiple NICs, you can take
advantage of the bandwidth from multiple NICs even if all of the NICs are not dedicated to running FT.
Store ISOs on Shared Storage for Continuous Access
Store ISOs that are accessed by virtual machines with Fault Tolerance enabled on shared storage that is
accessible to both instances of the fault tolerant virtual machine. If you use this configuration, the CD-
ROM in the virtual machine continues operating normally, even when a failover occurs.
Avoid Network Partitions
A network partition occurs when a vSphere HA cluster has a management network failure that isolates
some of the hosts from vCenter Server and from one another. See Network Partitions. When a partition
occurs, Fault Tolerance protection might be degraded.
vSphere Availability
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