Chapter 9 High Availability for FortiOS 5.0 : HA and failover protection : Synchronizing the configuration : Configuration settings that are not synchronized
  
Configuration settings that are not synchronized
The following settings are not synchronized among cluster units:
HA override.
HA device priority.
The virtual cluster priority.
The FortiGate unit host name.
The HA priority setting for a ping server (or dead gateway detection) configuration.
The system interface settings of the HA reserved management interface.
The HA default route for the reserved management interface, set using the ha‑mgt‑interface-gateway option of the config system ha command.
The primary unit synchronizes all other configuration settings, including the other HA configuration settings.