High Availability
How link and module failures affect primary chassis selection
If there are no failures and if you haven't configured any settings to influence primary chassis selection, the
chassis with the highest serial number to becomes the primary chassis.
Using the serial number is a convenient way to differentiate FortiGate-7000 chassis; so basing primary chassis
selection on the serial number is predictable and easy to understand and interpret. Also the chassis with the
highest serial number would usually be the newest chassis with the most recent hardware version. In many cases
you may not need active control over primary chassis selection, so basic primary chassis selection based on serial
number is sufficient.
In some situations you may want have control over which chassis becomes the primary chassis. You can control
primary chassis selection by setting the priority of one chassis to be higher than the priority of the other. If you
change the priority of one of the chassis, during negotiation, the chassis with the highest priority becomes the
primary chassis. As shown above, FortiGate-7000 FGCP selects the primary chassis based on priority before
serial number. For more information about how to use priorities, see
.
Chassis uptime is also a factor. Normally when two chassis start up their uptimes are similar and do not affect
primary chassis selection. However, during operation, if one of the chassis goes down the other will have a much
higher uptime and will be selected as the primary chassis before priorty and serial number are tested.
Verifying primary chassis selection
You can use the
diagnose sys ha status
command to verify which chassis has become the primary
chassis as shown by the following command output example. This output also shows that the chassis with the
highest serial number was selected to be the primary chassis.
diagnose
sys
ha
status
==========================================================================
Current slot: 1
Module SN: FIM04E3E16000085
Chassis HA mode: a-p
Chassis HA information:
[Debug_Zone HA information]
HA group member information: is_manage_master=1.
FG74E83E16000015:
Slave, serialno_prio=1, usr_priority=128, hostname=CH15
FG74E83E16000016: Master, serialno_prio=0, usr_priority=127, hostname=CH16
How link and module failures affect primary chassis selection
The total number of connected data interfaces in a chassis has a higher priority than the number of failed
modules in determining which chassis in a FortiGate-7000 HA configuration is the primary chassis. For example,
if one chassis has a failed FPM module and the other has a disconnected or failed data interface, the chassis with
the failed processor module becomes the primary unit.
For another example, the following
diagnose sys ha status
command shows the HA status for a cluster
where one chassis has a disconnected or failed data interface and the other chassis has a failed FPM module.
diagnose sys ha status
==========================================================================
Slot: 2 Module SN: FIM01E3E16000088
Chassis HA mode: a-p
Chassis HA information:
FortiGate-7000
Fortinet Technologies Inc.
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