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Cassandra Horizontal Scaling
This guide will give an overview on how KubeDB Ops-manager operator scales up or down Cassandra cluster replicas of various component such as Combined, Broker, Controller.
Before You Begin
- You should be familiar with the following
KubeDBconcepts:
How Horizontal Scaling Process Works
The following diagram shows how KubeDB Ops-manager operator scales up or down Cassandra database components. Open the image in a new tab to see the enlarged version.
The Horizontal scaling process consists of the following steps:
At first, a user creates a
CassandraCustom Resource (CR).KubeDBProvisioner operator watches theCassandraCR.When the operator finds a
CassandraCR, it creates required number ofPetSetsand related necessary stuff like secrets, services, etc.Then, in order to scale the various components (ie. ReplicaSet, Shard, ConfigServer, Mongos, etc.) of the
Cassandracluster, the user creates aCassandraOpsRequestCR with desired information.KubeDBOps-manager operator watches theCassandraOpsRequestCR.When it finds a
CassandraOpsRequestCR, it halts theCassandraobject which is referred from theCassandraOpsRequest. So, theKubeDBProvisioner operator doesn’t perform any operations on theCassandraobject during the horizontal scaling process.Then the
KubeDBOps-manager operator will scale the related PetSet Pods to reach the expected number of replicas defined in theCassandraOpsRequestCR.After the successfully scaling the replicas of the related PetSet Pods, the
KubeDBOps-manager operator updates the number of replicas in theCassandraobject to reflect the updated state.After the successful scaling of the
Cassandrareplicas, theKubeDBOps-manager operator resumes theCassandraobject so that theKubeDBProvisioner operator resumes its usual operations.
In the next docs, we are going to show a step by step guide on horizontal scaling of Cassandra cluster using CassandraOpsRequest CRD.