High Availability is required to ensure that application services supported by the edge such as firewall, NAT, and load balancing are available in the event of a hardware of a ESXi host where the Edge VM is running or software failure to a single ESG appliance. Edge HA minimizes the service disruption but does not provide a zero-downtime solution.

HA provided by the ESG is stateful and comes in the form of active and standby edge virtual machine appliances. As there are two virtual machines that effectively take the role of active/standby, it is good practice to ensure each appliance is located on separate resource pools and datastores to ensure that a hardware failure doesn't render both the active and standby appliances unserviceable.

The mechanism that one active ESG appliance uses to communicate with another is via a heartbeat, which by default is sending a hello every 15 seconds to signal that it is alive and healthy. In the event the standby appliance does...