Would split-brain problem happen in a 2-nodes NLB configuration?

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Would split-brain problem happen in a 2-nodes NLB configuration?

JasonYangJW 61

NLB assumes that a host is functioning normally within a cluster as long as it participates in the normal exchange of heartbeat messages between it and the other hosts. In a 2-nodes NLB configuration, when the heartbeat network is down but 2 servers still running, will it become a split-brain scenario?

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JiayaoZhu 3,926

Hi,

Thanks for posting on our forum!

The answer is yes. Basically, we have a RHS service in a cluster. RHS service is used to test if resources in a cluster is alive by sending and receiving heartbeats. After a 5-second and a 60-second waiting, if a resource is still no response, RHS service will down the resource and reboot itself to fix the down resource. So, if you find your RHS service marks your nodes as down while your nodes (which are a kind of cluster resource) are still running, you encounter split-brain in your cluster. You can read this article to know more about a split-brain status of a cluster and how to fix it:
https://www.45drives.com/community/articles/what-is-split-brain/

Please note: Information posted in the given link is hosted by a third party. Microsoft does not guarantee the accuracy and effectiveness of information.

Thanks for your support! Besides, would you please help me Accept Answer if you find my answer is helpful? An accepted blog can be put on top of our forum, so that people who have a similar issue can get access to their solution more quickly.

BR,
Joan

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JasonYangJW 61 Reputation points

2021-07-22T07:46:27.427+00:00

Thank you very much.
From the link you post, it suggests to solve the split-brain problem by a quorum, but as I know, a quorum is not needed in NLB (Network Load Balancing).
I found some article like the link bellow, saying that "Network load balancing does not use quorums", and in fact we don't have to configure something like quorum and the NLB cluster works fine.
https://techgenix.com/cluster-quorums/

So is there any solution to avoid the split-brain scenario in 2-nodes NLB cluster?
JiayaoZhu 3,926 Reputation points

2021-07-23T01:49:16.95+00:00

Hi,

Thanks for your reply!

After my research, so far I could only find the quorum solution. And if your NLB cluster supports the configuration of quorum (i.e. it doesn't need a quorum but supports the configuration), then I think you can still take this solution as a backup plan. Actually, quorum serves as a node to vote for the maintanence of cluster. Our storage systems are consensus-based and require majority for data consistency. That's why two node cluster is vulnerable to split-brain problem and should be treated as a temporary state when migrating to 3 or more nodes. So, another way to avoid the split-brain scenario in 2-nodes NLB cluster is to add another node, no matter it is a VM or a physical machine.

Thanks for your support!

BR,
Joan

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Would split-brain problem happen in a 2-nodes NLB configuration?

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