put ha cluster in maintenance mode preventing split brain scenario

pnobels · ‎02-09-2024

Hi,

i was wondering. Is there a way to put a ha cluster in maintenance mode? With maintenance mode i mean, there will be no response to heartbeat failures for example. Primary member remains active. Secondary remains not active. This would be handy in a situation where there is maintenance on the networking infrastructure between two sites, impacting the hearbeats between the nodes. And we want to prevent split brain scenario's...

Ofcourse, we can shutdown the secundary node. But since the used Fortigates cannot be powered on again remotely without someone going physically onsite to press the power button...

fricci_FTNT · ‎02-09-2024

Hi @pnobels ,

As far as I am aware there is not maintenance mode in FortiGate. If you cannot shutdown the secondary node and you do not want the secondary node to take over, you can do the following (if applicable):

1- shutdown/disable all data ports on secondary unit (on the connected switch side, not on the FGT side). In that case the secondary unit will not take over and even if it becomes the primary due to split brain, it will not affect your network data. Bear in mind that if you use the same MGMT IP (not reserved MGMT interface) and the HA breaks between primary and secondary, you might not be able to access secondary unit through MGMT IP remotely.

2- If you disable one or more FortiGate monitored interfaces (on switch side) on the secondary unit, it will not be able to take over. That would not prevent split brain scenarios anyway. [https://community.fortinet.com/t5/FortiGate/Technical-Tip-FortiGate-HA-Primary-unit-selection-proces... ]

Hope this helps.

Best regards,

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View solution in original post

fricci_FTNT · ‎02-09-2024

Hi @pnobels ,

As far as I am aware there is not maintenance mode in FortiGate. If you cannot shutdown the secondary node and you do not want the secondary node to take over, you can do the following (if applicable):

1- shutdown/disable all data ports on secondary unit (on the connected switch side, not on the FGT side). In that case the secondary unit will not take over and even if it becomes the primary due to split brain, it will not affect your network data. Bear in mind that if you use the same MGMT IP (not reserved MGMT interface) and the HA breaks between primary and secondary, you might not be able to access secondary unit through MGMT IP remotely.

2- If you disable one or more FortiGate monitored interfaces (on switch side) on the secondary unit, it will not be able to take over. That would not prevent split brain scenarios anyway. [https://community.fortinet.com/t5/FortiGate/Technical-Tip-FortiGate-HA-Primary-unit-selection-proces... ]

Hope this helps.

Best regards,

---
If you have found a useful article or a solution, please like and accept it to make it easily accessible to others.

AEK · ‎02-09-2024

Hello @pnobels

In addition to @fricci_FTNT 's response, in case you just afraid of losing HB links, you can temporarily add as many low priority HBs as you want on prod links, if you are sure that these prod links are not exposed to connectivity failure.

In such way even if you lose the two main HBs you'll not have split brain.

AEK