This host-level alert is triggered if storage capacity if full on the DataNode (90%
critical). It uses the check_datanode_storage.php
plug-in which checks the DataNode JMX
Servlet for the Capacity and Remaining properties.
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