Using Ambari Core Services
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HDFS NameNodes

Metrics to see status for the NameNodes.

Table 1. HDFS NameNodes metrics descriptions
Row Metrics Description
RPC CLIENT QUEUE TIME RPC Client Port Queue Time Average time that a RPC request (on the RPC port facing to the HDFS clients) waits in the queue.
RPC Client Port Queue Num Ops Total number of RPC requests in the client port queue.
RPC CLIENT PORT PROCESSING TIME RPC Client Port Processing Time Average RPC request processing time in milliseconds, on the client port.
RPC Client Port Processing Num Ops Total number of RPC active requests through the client port.
GC COUNT & GC TIME GC Count Shows the JVM garbage collection rate on the NameNode.
GC Time Shows the garbage collection time in milliseconds.
GC PAR NEW GC Count Par New The number of times young generation garbage collection happened.
GC Time Par New Indicates the duration of young generation garbage collection.
GC EXTRA SLEEP & WARNING THRESHOLD EXCEEDED GC Extra Sleep Time Indicates total garbage collection extra sleep time.
GC Warning Threshold Exceeded Count Indicates number of times that the garbage collection warning threshold is exceeded.
RPC CLIENT PORT QUEUE & BACKOFF RPC Client Port Queue Length Indicates the current length of the RPC call queue.
RPC Client Port Backoff Indicates number of client backoff requests.
RPC SERVICE PORT QUEUE & NUM OPS RPC Service Port Queue Time Average time a RPC request waiting in the queue, in milliseconds. These requests are on the RPC port facing to the HDFS services, including DataNodes and the other NameNode.
RPC Service Port Queue Num Ops Total number of RPC requests waiting in the queue. These requests are on the RPC port facing to the HDFS services, including DataNodes and the other NameNode.
RPC SERVICE PORT PROCESSING TIME & NUM OPS RPC Service Port Processing Time Average RPC request processing time in milliseconds, for the service port.
RPC Service Port Processing Num Ops Number of RPC requests processed for the service port.
RPC SERVICE PORT CALL QUEUE LENGTH & SLOW CALLS RPC Service Port Call Queue Length The current length of the RPC call queue.
RPC Service Port Slow Calls The number of slow RPC requests, for the service port.
TRANSACTIONS SINCE LAST EDIT & CHECKPOINT Transactions Since Last Edit Roll Total number of transactions since the last editlog segment.
Transactions Since Last Checkpoint Total number of transactions since the last editlog segment checkpoint.
LOCK QUEUE LENGTH & EXPIRED HEARTBEATS Lock Queue Length Shows the length of the wait Queue for the FSNameSystemLock.
Expired Heartbeats Indicates the number of times expired heartbeats are detected on NameNode.
THREADS BLOCKED / WAITING Threads Blocked Indicates the number of threads in a BLOCKED state, which means they are waiting for a lock.
Threads Waiting Indicates the number of threads in a WAITING state, which means they are waiting for another thread to perform an action.