NSX Advanced Load Balancer Service Engines groups support the following HA modes:
Elastic HA: Provides fast recovery for individual virtual services following failure of the Service Engine. Depending on the mode, the virtual service is either already running on multiple SEs or is quickly placed on another SE. The following modes of cluster HA are supported:
N + M
Legacy HA for the Service Engines: Emulates the operation of 2-device hardware active/standby HA configuration. The active SE carries all the traffic for a virtual service placed on it. The other SE in the pair is the standby for the virtual service, which does not carry traffic while the other active SE is healthy.