Chapter 9 High Availability for FortiOS 5.0 : An introduction to the FGCP : Synchronizing the configuration (and settings that are not synchronized)
  
Synchronizing the configuration (and settings that are not synchronized)
The FGCP uses a combination of incremental and periodic synchronization to make sure that the configuration of all cluster units is synchronized to that of the primary unit. This means that in most cases you only have to make a configuration change once to have it synchronized to all cluster units.
Some configuration settings are not synchronized to support some aspects of FortiGate operation. The following settings are not synchronized among cluster units:
• The FortiGate unit host name. Allows you to identify cluster units.
• HA override (“HA override”).
• HA device priority (“Primary unit selection and device priority”).
• Virtual cluster 1 and Virtual cluster 2 device priorities (“Virtual clustering and load balancing or VDOM partitioning”)
• The HA priority (ha-priority) setting for a ping server or dead gateway detection configuration (“Remote link failover”).
• The system interface settings of the FortiGate interface that becomes the HA reserved management interface (“Managing individual cluster units using a reserved management interface”).
• The default route for the reserved management interface, set using the ha‑mgt‑interface-gateway option of the config system ha command (“Managing individual cluster units using a reserved management interface”).
• The dynamic weighted load balancing thresholds and high and low watermarks (“Dynamically optimizing weighted load balancing according to how busy cluster units are”).