About the Default Affinity and Anti-Affinity Settings for TimesTenClassic Objects

Kubernetes affinity and anti-affinity settings constrain how Pods are scheduled on a Node. See Affinity and anti-affinity in the Kubernetes documentation.

By default, the TimesTen Operator adds the following affinity and anti-affinity settings to Pods that are created when deploying a TimesTenClassic object:

• A nodeAffinity setting that instructs Kubernetes to provision TimesTen Pods on nodes with the proper architecture (either amd64 or arm64). For more information about these architectures, see About Deploying in a Multi-Architecture Kubernetes Cluster in this book. This architecture setting is required.

• A podAntiAffinity section that instructs Kubernetes to schedule Pods for a TimesTenClassic object on different nodes, if possible. This section is preferred. Because the anti-affinity setting is preferred (a lesser constraint), Kubernetes can schedule multiple Pods on the same Node if resource constraints make it necessary. For example, although not recommended, an active standby pair of TimesTen databases can be provisioned in a one Node cluster. However, if two or more Nodes are available, Kubernetes attempts to schedule TimesTen Pods on different Nodes.

If you provide your own affinity section in a TimesTenClassic object definition, the TimesTen Operator uses your affinity section and does not modify it.

Note:

If you specify a nodeAffinity.requiredDuringSchedulingIgnoredDuringExecution section, the TimesTen Operator adds the arch clause to it.

The following snippet shows the default affinity and anti-affinity settings for a TimesTenClassic object named sample.

      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: kubernetes.io/arch
                operator: In
                values:
                - amd64
        podAntiAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
          - podAffinityTerm:
              labelSelector:
                matchLabels:
                  database.timesten.oracle.com: sample
              topologyKey: kubernetes.io/hostname
            weight: 50