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Fortimaster1
Fortimaster1
Explorer
January 9, 2026
Question

Doubts about Monitored interface in HA Active Pasive

  • January 9, 2026
  • 2 replies
  • 383 views

Hi all.

 

I have Fortigate 600E with 7.4.9 FortIOS. I have an HA cluster active pasive:

Unit 1 has 100 Priority.

Unit 2 has 50 Priority.

I have too, override disable.

 

If I put down a monitored interface in Unit 1, cluster converges and Unit 2 becomes active. But, if I turn UP again disconnected interface in Unit 1, Unit 1 becomes active again.

 

Why  doesn't unit2 stay Active, if I have configured the cluster with HA Override disable? If it is not properly configured, what should I do?

 

Thanks

2 replies

KevinGue
KevinGue
Explorer II
January 9, 2026

Read this: https://community.fortinet.com/t5/FortiGate/Technical-Tip-FortiGate-HA-Primary-unit-selection-process-when/ta-p/249745

 

Specifically pay attention to the part about the HA uptime and check this on your units after a failover. If it falls in the default 300 seconds the uptime won't be considered.

Toshi_Esumi
SuperUser
Toshi_Esumi
SuperUser
January 9, 2026

Most likely the unit1's S/N is higher than unit2 when uptime difference was <5min. If you check "get sys ha status" it would tell you why they swapped like this.

Primary selected using:
<2026/01/09 00:12:04> vcluster-1: FG1K0FTBxxxxxxxxx is selected as the primary because its serialno is larger than peer member FG1K0FTByyyyyyyyy.

Toshi

Fortimaster1
Fortimaster1Author
Explorer
January 13, 2026

Thanks ¡¡ The change of unit happens much later of these 5 first minutes. This is why I don't understand this behaviour:

The message sais; "is selected as the primary because its override priority is larger than peer member FG6Hxxxxx".

Why, if I have override disable?

Toshi_Esumi
SuperUser
Toshi_Esumi
SuperUser
January 13, 2026

Found a KB answering your question. Even when it's "disabled" the priority is the 3rd factor (before the 4th factor:S/N) to elect a primary.
If you don't want the priority affecting the primary election, you need to set the same number on both sides.
https://community.fortinet.com/t5/FortiGate/Technical-Tip-FortiGate-HA-Primary-unit-selection-process-when/ta-p/249745

Toshi

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