Fortinet 5.0 Patch 6 How HA chooses the active appliance, I

Fortinet 44 FortiWeb 5.0 Patch 6 Administration Guide

How HA chooses the active appliance

An HA pair may or may not resume their active and standby roles when the failed appliance

resumes responsiveness to the heartbeat.

Since the current active appliance will by definition have a greater uptime than a failed previous

active appliance that has just returned online, assuming each has the same number of available

ports, the current active appliance usually retains its status as the active appliance, unless

Override is enabled. If Override is enabled, and if the Device Priority setting of the returning

appliance is higher, it will be elected as the active appliance in the HA cluster.

If Override is disabled, HA considers (in order)

1. The most available ports

For example, if two FortiWeb appliances, FWB1 and FWB2, were configured to monitor two

ports each, and FWB2 has just one port currently available according to Port Monitor, FWB1

would become the active appliance, regardless of uptime or priority. But if both had 2

available ports, this factor alone would not be able to determine which appliance should be

active, and the HA cluster would proceed to the next consideration.

2. The highest uptime value

Uptime is reset to zero if an appliance fails, or the status of any monitored port (per Port

Monitor) changes.

3. The smallest Device Priority number (that is, 1 has the highest priority)

4. The highest-sorting serial number

If Override is enabled, HA considers (in order)

1. The most available ports

2. The smallest Device Priority number (that is, 1 has the highest priority)

3. The highest uptime value

4. The highest-sorting serial number

If the heartbeat link occurs through switches or routers, and the active appliance is very busy, it

might require more time to establish a heartbeat link through which it can negotiate to elect the

active appliance. You can configure the amount of time that a FortiWeb appliance will wait after

it boots to establish this connection before assuming that the other appliance is unresponsive,

and that it should become the active appliance. For details, see the boot-time

<seconds_int> setting in the FortiWeb CLI Reference.