Firepower FMC HA

 1. Configuration

https://www.cisco.com/c/en/us/support/docs/security/secure-firewall-management-center/221089-configure-high-availability-on-fmc.html

2. Upgrade

https://www.cisco.com/c/en/us/support/docs/security/secure-firewall-management-center/220602-upgrade-fmc-in-high-availability.html

On FTD with HA FMC:

> show managers
Type                      : Manager
Host                      : 192.168.100.41
Display name              : 192.168.100.41
Version                   : 7.4.3 (Build 315)
Identifier                : e14cfec8-d542-11f0-acf5-b9807ef5d1c1
Registration              : Completed
Management type           : Configuration and analytics

Type                      : Manager
Host                      : 192.168.100.42
Display name              : 192.168.100.42
Version                   : 7.4.3 (Build 315)
Identifier                : 86ef50fe-d545-11f0-bf93-84dce0dcf86f
Registration              : Completed
Management type           : Configuration and analytics

>

Break HA

After break HA, both FMCs will be in standalone mode, only this FMC has registered devices, peer has no registered devices.