CODEWITHSUNDEEP
cassandra
Christopher Crowe
Christopher Crowe

Reputation: 56

What is the proper way to seed a 3 node cluster?

A little background if it helps, I'm preparing a 3 node cluster (all in the same rackspace). I want 3 nodes for optimal consistency and resilience in the smallest footprint and I am not concerned with replicating the cluster to another region.

One question I have is regarding seed nodes. I know that it is not a good idea to make every node in your cluster a seed, but in the case of 3 nodes, should I just go ahead and do that? Or should I just make a subset of the three nodes seed nodes? Confused as to how pick how many or which ones (all the machines are identical so which ones probably isn't an issue).

Upvotes: 1

Views: 637

Answers (3)

Mert Karabulut
Mert Karabulut

Reputation: 13

Internode communications (gossip)The seed node designation has no purpose other than bootstrapping the gossip process for new nodes joining the cluster. Seed nodes are not a single point of failure, nor do they have any other special purpose in cluster operations beyond the bootstrapping of nodes.

Making every node a seed node is not recommended because of increased maintenance and reduced gossip performance. Gossip optimization is not critical, but it is recommended to use a small seed list.

So the best practice is setting 1 seed node for a 3 node cluster.

Upvotes: 0

Bruno Trinta
Bruno Trinta

Reputation: 26

It is not recommanded to make all nodes seed nodes when initializing a multiple node cluster.

Determine which nodes will be seed nodes. Do not make all nodes seed nodes. Please read Internode communications (gossip).

Although it is best practice to have 1 seed per 3 nodes in the cluster, it is also best practice to have multiple seeds for one data center when you configure your cluster.

Note: It is a best practice to have more than one seed node per datacenter.

I suggest you make 2 seed out of your 3 nodes. Let us know what option you went for.

Upvotes: 0

Matija Gobec
Matija Gobec

Reputation: 880

Seed nodes are nothing special but an initial contact point address. Best practice is to have 1 seed node per 3 nodes in the cluster but this varies depending on the deployment. You can also put all three IPs in the seed node list without any problems.

Upvotes: 2

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