HDFS and MapReduce - Cloudera Administration - page 37

◦ DFS Remaining% : This displays the total HDFS space remaining shown
as percentage.
◦ Block Pool Used : This displays the total space utilized by the current
namespace.
◦ Block Pool Used% : This displays the total space utilized by the current
namespace shown as percentage. As you can see in the preceding screen-
shot, in this case, the value matches that of the DFS Used% parameter.
This is because there is only one namespace (one namenode) and HDFS
is not federated.
◦ DataNodes usages% (Min, Median, Max, stdDev) : This displays the
usages across all datanodes in the cluster. This helps administrators
identify unbalanced nodes, which may occur when data is not uniformly
placed across the datanodes. Administrators have the option to rebalance
the datanodes using a balancer.
◦ Live Nodes : This link displays all the datanodes in the cluster as shown
in the following screenshot:
◦ Dead Nodes : This link displays all the datanodes that are currently in a
dead state in the cluster. A dead state for a datanode daemon is when the
datanode daemon is not running or has not sent a heartbeat message to
the namenode daemon. Datanodes are unable to send heartbeats if there
exists a network connection issue between the machines that host the
datanode and namenode daemons. Excessive swapping on the datanode