Scale Up Cassandra in different versions of OpenShift

For Red Hat OpenShift Enterprise version 3.1 and 3.2, and Red Hat OpenShift Container Platform version 3.3 and 3.4

• As per the This page is not included, but the link has been rewritten to point to the nearest parent document.documentation for this, you will need to use a template that should be in the openshift-infra project. You can check this with the following command:

  # oc get template --all-namespaces | grep cassandra
  openshift-infra    hawkular-cassandra-node-emptydir    4 (1 blank)       1
  openshift-infra    hawkular-cassandra-node-pv                6 (1 blank)       2
  openshift-infra    hawkular-cassandra-services                 0 (all set)       2
  

• If you have persistent storage setup for your existing cassandra instance, you will need to create a New PersistentVolume and will then use the hawkular-cassandra-node-pv template. Please take note of the storage size, we will use this later.

• If you are not using persistent storage, you will simply use the hawkular-cassandra-node-emptydir template

• After determining which template to use, and creating any PVs, you will then need to process the template, adding the various, important, variables:

  # If not using persistent storage, the only variable that needs to be set is the number of cassandra pods you need:
  oc process hawkular-cassandra-node-emptydir NODE=# | oc create -f -
  
  # If using persistent storage, you will need to specify the number of cassandra pods you need as well as the size of the PV created:
  oc process hawkular-cassandra-node-pv NODE=2 PV_SIZE=50Gi | oc create -f -
  

For OpenShift Container Platform version 3.5 and above

• To properly scale up and have two replicas of Cassandra, you will need to create a new, separate PV so this second Cassandra instance has persistent storage, as well, and then run the metrics install playbook and add this option with -e openshift_metrics_cassandra_replicas=2 as well as the options for the storage.

For example:

    ansible-playbook [-i </path/to/inventory>] <OPENSHIFT_ANSIBLE_DIR>/byo/openshift-cluster/openshift-metrics.yml \
       -e openshift_metrics_install_metrics=True \
       -e openshift_metrics_cassandra_replicas=2 \
       -e openshift_metrics_cassandra_storage_type=pv \
       -e openshift_metrics_cassandra_pvc_size=1Ti