Expand Cassandra persistent volumes

This process allows you to expand the persistent volumes used by the Apigee hybrid Cassandra database to accommodate greater storage needs without needing to create new nodes just to provide more storage.

Overview

The Apigee hybrid cassandra component uses persistent volumes to store data. The size of the persistent volume is defined during installation and initial configuration. This initial storage size is an immutable value and cannot be changed. Therefore, any new node added to the cluster will use the same persistent volume size.

It is possible to increase the size of the existing persistent volume by making the changes directly on the Persistent volume Claim, but new nodes will still use the smaller initial persistent volume size.

If your hybrid Cassandra database is nearing its storage capacity, you can use this procedure to expand the existing persistent volumes and allow new nodes to expand their persistent volumes as well.

Expand Cassandra persistent volumes

  1. Update the volume size to the desired size: 
    kubectl -n apigee edit pvc
  2. Check the updated volume capacity: 
     kubectl get pvc -n apigee
     
    NAME                                STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
cassandra-data-apigee-cassandra-default-0   Bound    pvc-92234ba7-941b-4dab-82c6-8a5288a2c8d4   100Gi      RWO            standard       21m
cassandra-data-apigee-cassandra-default-1   Bound    pvc-6be911fc-91f7-465d-a02e-933428ee10b2   100Gi      RWO            standard       20m
cassandra-data-apigee-cassandra-default-2   Bound    pvc-14ba34e4-fd5c-4d59-8413-a331dcad3404   100Gi      RWO            standard       19m
  3. Set replicas to 0 for apigee-controller-manager deployments in the apigee-system namespace: 
    1. kubectl get deployments -n apigee-system
       
      NAME                        READY   UP-TO-DATE   AVAILABLE   AGE
apigee-controller-manager   1/1     1            1           28m
       
    2. kubectl edit deployments -n apigee-system apigee-controller-manager
       
    3. kubectl get deployments -n apigee-system
       
      NAME                        READY   UP-TO-DATE   AVAILABLE   AGE
apigee-controller-manager   0/0     0            0           30m
  4. Delete STS without cascade deletion: 
    1. kubectl -n apigee delete sts --cascade=false apigee-cassandra
    2. kubectl get sts -n apigee
       
      No resources found in apigee namespace.
  5. Update the your overrides file with new volume size that you specified when you edited the pvc: 
    cassandra:
  storage:
    capacity: 100Gi
  6. Apply the updated configuration to the cluster: 
    ../apigeectl apply --datastore -f overrides/overrides.yaml
     
    Parsing file: config/values.yaml
Parsing file: overrides/overrides.yaml
cleansing older AD's (v1alpha1) istio resources...

Invoking "kubectl apply" with YAML config...

apigeedatastore.apigee.cloud.google.com/apigee-cassandra unchanged
  7. Update the controller deployment replicas to previous their state (`1`): 
    kubectl edit deployments -n apigee-system apigee-controller-manager
  8. Check if the newly created sts has the updated storage size: 
    kubectl get sts -n apigee apigee-cassandra -o yaml |grep storage
     
    storage: 100Gi

  9. Check if C* pods data volume got updated with new size: 

    kubectl exec -n apigee -it apigee-cassandra-default-0 -- df -h|grep "/opt/apigee/data"
     
    /dev/sdb         99G   69M   99G   1% /opt/apigee/data