Setting up dedicated nodes for your Db2 on Red Hat OpenShift deployment

You can dedicate one or more worker nodes to your Db2 on Red Hat OpenShift database service. The nodes are then used exclusively by the database containers or pods.

About this task

Db2® Warehouse on Red Hat® OpenShift® uses the concepts of taint and toleration to dedicate Db2 Warehouse to particular nodes. Nodes are tainted and labeled:

  • A taint prevents pods from being deployed on a tainted node.
  • A label allows for a pod with a matching toleration to be treated as an exception.

Taint and toleration work together to provide node exclusivity to deploying Db2 Warehouse on particular nodes

Perform these steps for each worker node that you plan to dedicate to the database deployment. The steps use Db2 Warehouse on Red Hat OpenShift CLI commands. The node_name is the name of a worker node on which you plan to host Db2 Warehouse.

Considerations for software-defined storage (such as OpenShift Container Storage)

When storage and compute share the same nodes, some additional considerations apply so that Db2 Warehouse and software-defined storage can be properly scheduled on the same worker nodes. See the optional Step 2 below.

Procedure

  1. Retrieve the name of the worker node that you want to dedicate to Db2 Warehouse: 
    oc get nodes
  2. Optional: If you are using OpenShift Container Storage, see the OpenShift documentation for information about dedicating nodes that is specific to that platform.
  3. Taint the node with the NoSchedule effect and safely evict all of the pods from that node: 
    oc adm taint node node_name icp4data=dedicated_specifier:NoSchedule --overwrite
oc adm drain node_name
oc adm uncordon node_name

    Where dedicated_specifier is an identifier that is used to deploy a database only on nodes that have the dedicated_specifier label. By default, the dedicated_specifier for Db2 Warehouse is database-db2oltp. The --overwrite flag is only required if the node is already tainted or labeled and ensures that the taint or label is replaced.

  4. Label the node: 
    oc label node node_name icp4data=dedicated_specifier --overwrite
  5. Optional: Verify that the node is labeled: 
    oc get node --show-labels