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MariaDB Vertical Scaling

This guide will give an overview on how KubeDB Ops Manager vertically scales up MariaDB.

Before You Begin

• You should be familiar with the following KubeDB concepts:
  • MariaDB
  • MariaDBOpsRequest

How Vertical Scaling Process Works

The following diagram shows how KubeDB Ops Manager scales up or down MariaDB database components. Open the image in a new tab to see the enlarged version.

  

The vertical scaling process consists of the following steps:

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

2. KubeDB Community operator watches the MariaDB CR.

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

4. Then, in order to update the resources(for example CPU, Memory etc.) of the MariaDB database the user creates a MariaDBOpsRequest CR with desired information.

5. KubeDB Enterprise operator watches the MariaDBOpsRequest CR.

6. When it finds a MariaDBOpsRequest CR, it halts the MariaDB object which is referred from the MariaDBOpsRequest. So, the KubeDB Community operator doesn’t perform any operations on the MariaDB object during the vertical scaling process.

7. Then the KubeDB Enterprise operator will update resources of the PetSet Pods to reach desired state.

8. After the successful update of the resources of the PetSet’s replica, the KubeDB Enterprise operator updates the MariaDB object to reflect the updated state.

9. After the successful update of the MariaDB resources, the KubeDB Enterprise operator resumes the MariaDB object so that the KubeDB Community operator resumes its usual operations.

Vertical Scaling Modes

KubeDB actuates vertical scaling in one of two modes, selected through the spec.verticalScaling.mode field of the MariaDBOpsRequest:

• Restart (default): The operator patches the PetSet with the new resources and restarts the Pods (one at a time, honoring the database’s failover rules) so they come back with the updated CPU and Memory. This works on every Kubernetes cluster.
• InPlace: The operator resizes the running containers in place using the Kubernetes in-place Pod resize (pods/resize subresource) — no Pod restart, so scaling happens without downtime or failover. If a Node cannot accommodate the new resources (the resize is reported Infeasible), the operator automatically falls back to the Restart behavior for that Pod. For a distributed MariaDB deployment, in-place resize is not possible, so InPlace automatically degrades to Restart.

If spec.verticalScaling.mode is omitted, it defaults to Restart.

Note: InPlace mode relies on the Kubernetes InPlacePodVerticalScaling feature gate, which is enabled by default from Kubernetes v1.33. On older clusters, or when the feature gate is disabled, use Restart mode.

In the next docs, we are going to show a step by step guide on updating resources of MariaDB database using MariaDBOpsRequest CRD.