Current behaviour
When 3scale is deployed with the Operator you can increase the resource request for system-storage and system-mysql/postgresql storage in the APImanager CRD. For example:
For system storage:

system:
  fileStorage:
    persistentVolumeClaim:
      resources:
        requests:  10Gi

For system-mysql storage:

system:
  database:
    mysql:
      persistentVolumeClaim:
        resources:
          requests:  10Gi
 

 
This was introduced here and documented here.

However it is not possible for system-redis and backend-redis. You can only specify the storageclass. 

• SystemRedisPersistentVolumeClaimSpec
• BackendRedisPersistentVolumeClaimSpec

 
Expected behaviour
Be able to add resource requests to backend and system redis as well.