You can have a scenario in which both Cores in an HA configuration fail at the same time; for example, a major power outage. In this case, there is no opportunity for either Core to realize that its peer has failed.

When both Core appliances reboot, each peer knows that it has failed but does not have status from the other to say that it had been in an ActiveSolo state. Therefore, both Cores remain in the Inactive state. This state ensures that neither Core is projecting exports until you manually activate the correct Core. To activate the correct Core, choose Configure > Failover: Failover Configuration and select Activate Config.

After you activate the correct Core, it transitions to ActiveSolo. Both Core appliances transition to ActiveSelf.