To provide availability, VMware vSphere HA protects against physical host failures and restart-failed virtual machines using either the third-party load balancing virtual appliance or the vCloud Networking and Security Edge-based solution. This affords about 99.9% uptime for the load balancing functionality (based on VMware HA availability numbers).

You can improve availability for the Edge load balancer by running it in native High Availability mode. This affords the Edge an almost instantaneous failover, with session preservation.