This alert is triggered if storage capacity is full on the DataNodes. All the local data partitions storing HDFS data are checked against the total capacity across all the partitions. It uses the check_snmp_storage 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
