CODEWITHSUNDEEP
cassandranosqlreplicationcassandra-3.0
Dinesh Choubey
Dinesh Choubey

Reputation: 41

Three node Cassandra cluster all nodes configured different rack in same dc

I am a newbie in Cassandra. In our production environment three node Cassandra clusters are running and serving production traffic but I have below mentioned doubts:-

1) All nodes are configured in different racks i.e rack 1, rack 2 and rack 3 in the same dc. Is it fine or does this configuration have some drawbacks?

2) We are using rf2 and network topology for all the keyspaces except system tables and these system tables are configured with rf2 and simplestrategy ..is it fine or does this need to be changed? should we increase the replication factor of system_auth? ..please let me know..

3) Now I want to add another node in the same dc, what will be the best procedure to do the same without impacting the live traffic? Cassandra version is Apache cassandra 3.11.

Thanks in advance..

Upvotes: 0

Views: 1135

Answers (2)

Siddharth Mittal
Siddharth Mittal

Reputation: 96

Cassandra is designed as a distributed system. Cassandra’s distributed architecture is specifically tailored for multiple-data center deployment. These features are robust and flexible enough that you can configure the cluster for optimal geographical distribution, for redundancy for fail-over and disaster recovery.

Multiple data center deployments are excellent for global solutions where in some applications are operational in one region and other applications in another region and yet using a single cluster of Cassandra which is working in multiple data centers across regions.

For single region applications, still having multiple data-centers is preferred option because it provides disaster recovery even in case one region goes down.

Ans 1) For a single DC Cassandra cluster , recommendation is to have 4 nodes with RF3. Rack 1 with 2 nodes and Rack 2 with 2 nodes. Remember that nodes in the same rack have faster network than nodes in different racks. With two nodes on the same Rack, queries with LOCAL_QUORUM will be faster as compared to queries on a cluster with all nodes on different racks.

If you are not concerned with the query latency , all nodes in different racks (3 racks) will give better disaster recovery as compared with two RACK deployment. Having said that, it's always recommended to use multi DC deployments for production cluster.

Ans 2) It’s always recommended to increase the replication factor of System_auth keyspace and change the replication class to NetworkTopologyStrategy. Please follow this documentation for more details https://docs.datastax.com/en/security/6.0/security/secSystemKeyspace.html

Ans 3) Yes, You can add a new node to existing cluster with ease without impacting the traffic. Please follow this documentation for more details: https://docs.datastax.com/en/archived/cassandra/3.0/cassandra/operations/opsAddNodeToCluster.html

Upvotes: 0

LetsNoSQL
LetsNoSQL

Reputation: 1538

Ans 1) It seems good to have Cassandra nodes in different racks for availability and fault tolerance . Ans 2) You must increase RF on system_auth so that you can avoid cqlsh login issue from other nodes. Ans 3) You can add new node without affecting the live traffic on existing cluster. please follow below procedure. http://cassandra.apache.org/doc/latest/operating/topo_changes.html

Upvotes: 0

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