https://community.cloudera.com/t5/Support-Questions/Solution-for-quot-slow-readprocessor-quot-warnings/m-p/122047#M84803 <P>Right now I can think of 3 possible scenario which might create this issue.</P><P>1. Check the datanode logs corresponding to that block id, If there is any issue with the disks then probably you will see some messages like below. In case you can't find these messages then you still need take a look at disks IO</P><PRE>WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Slow BlockReceiver write data to disk cost:200ms (threshold=15ms)</PRE><P>OR</P><PRE>WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Slow BlockReceiver write packet to mirror took 986ms (threshold=300ms)</PRE><P>2. check datanode logs and it's GC pattern because a long GC pause can also cause this issue.</P><P>3. If datanode doesn't show any disk and GC issues then the networks latency b/w client and datanode could be a culprit, you can use iperf or other network tool to check latency.</P> Fri, 11 Mar 2016 01:21:35 GMT jyadav 2016-03-11T01:21:35Z