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This guide will give an overview on how KubeDB Ops-manager operator expand the volume of various component of MongoDB
such as ReplicaSet, Shard, ConfigServer, Mongos, etc.
KubeDB
concepts:The following diagram shows how KubeDB Ops-manager operator expand the volumes of MongoDB
database components. Open the image in a new tab to see the enlarged version.
The Volume Expansion process consists of the following steps:
At first, a user creates a MongoDB
Custom Resource (CR).
KubeDB
Provisioner operator watches the MongoDB
CR.
When the operator finds a MongoDB
CR, it creates required number of StatefulSets
and related necessary stuff like secrets, services, etc.
Each StatefulSet creates a Persistent Volume according to the Volume Claim Template provided in the statefulset configuration. This Persistent Volume will be expanded by the KubeDB
Ops-manager operator.
Then, in order to expand the volume of the various components (ie. ReplicaSet, Shard, ConfigServer, Mongos, etc.) of the MongoDB
database the user creates a MongoDBOpsRequest
CR with desired information.
KubeDB
Ops-manager operator watches the MongoDBOpsRequest
CR.
When it finds a MongoDBOpsRequest
CR, it halts the MongoDB
object which is referred from the MongoDBOpsRequest
. So, the KubeDB
Provisioner operator doesn’t perform any operations on the MongoDB
object during the volume expansion process.
Then the KubeDB
Ops-manager operator will expand the persistent volume to reach the expected size defined in the MongoDBOpsRequest
CR.
After the successfully expansion of the volume of the related StatefulSet Pods, the KubeDB
Ops-manager operator updates the new volume size in the MongoDB
object to reflect the updated state.
After the successful Volume Expansion of the MongoDB
components, the KubeDB
Ops-manager operator resumes the MongoDB
object so that the KubeDB
Provisioner operator resumes its usual operations.
In the next docs, we are going to show a step by step guide on Volume Expansion of various MongoDB database components using MongoDBOpsRequest
CRD.