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ZooKeeper Volume Expansion

This guide will give an overview on how KubeDB Ops-manager operator expand the volume of ZooKeeper cluster nodes.

Before You Begin

• You should be familiar with the following KubeDB concepts:
  • ZooKeeper
  • ZooKeeperOpsRequest

How Volume Expansion Process Works

The following diagram shows how KubeDB Ops-manager operator expand the volumes of ZooKeeper database components. Open the image in a new tab to see the enlarged version.

  

The Volume Expansion process consists of the following steps:

1. At first, a user creates a ZooKeeper Custom Resource (CR).

2. KubeDB Provisioner operator watches the ZooKeeper CR.

3. When the operator finds a ZooKeeper CR, it creates required number of Petsets and related necessary stuff like secrets, services, etc.

4. Each petset creates a Persistent Volume according to the Volume Claim Template provided in the PetSet configuration. This Persistent Volume will be expanded by the KubeDB Ops-manager operator.

5. Then, in order to expand the volume the ZooKeeper database the user creates a ZooKeeperOpsRequest CR with desired information.

6. KubeDB Ops-manager operator watches the ZooKeeperOpsRequest CR.

7. When it finds a ZooKeeperOpsRequest CR, it halts the ZooKeeper object which is referred from the ZooKeeperOpsRequest. So, the KubeDB Provisioner operator doesn’t perform any operations on the ZooKeeper object during the volume expansion process.

8. Then the KubeDB Ops-manager operator will expand the persistent volume to reach the expected size defined in the ZooKeeperOpsRequest CR.

9. After the successful Volume Expansion of the related Petset Pods, the KubeDB Ops-manager operator updates the new volume size in the ZooKeeper object to reflect the updated state.

10. After the successful Volume Expansion of the ZooKeeper components, the KubeDB Ops-manager operator resumes the ZooKeeper 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 ZooKeeper database components using ZooKeeperOpsRequest CRD.