There are many combinations of products or appliances available under the overall term Firepower, each with its own HA capabilities. In general, they are:
1. Firepower Management Center (FMC). HA possible between physical appliances (not available on FMC VM).
2. ASA with FirePOWER service module. HA and clustering available among the base ASAs. Modules aren't HA by themselves but can be managed as a group using FMC.
3. ASA or Firepower appliance running Firepower Threat Defense (FTD) image. HA only currently available on Firepower 2100 series running FTD 6.2.1 (NOT the ASA or Firepower 4100 and 9300 series). We expect this to change in the near future to expand to all other FTD platforms.
4. Firepower appliance running Firepower software (either "classic" appliances like the 8000 series or new ones like the 4100 and 9300 series). Active/Standby HA available. Details are all found in the configuration guide here:
https://www.cisco.com/c/en/us/td/docs/security/firepower/620/configuration/guide/fpmc-config-guide-v62/7000_and_8000_series_device_high_availability.html
You can also do stacking (8000 series) and clustering (Firepower 4100 series and 9300 appliances) for increased throughput.
