This service-level alert is triggered if the storage if full on a certain percentage
of DataNodes (10% warn, 30% critical). It uses the check_aggregate.php plug-in which
aggregates the result from the check_datanode_storage.php plug-in.
If cluster still has storage, use Balancer to distribute the data to relatively less used DataNodes
If the cluster is full, delete unnecessary data or add additional storage by adding either more DataNodes or more or larger disks to the DataNodes. After adding more storage run Balancer
