https://community.cloudera.com/t5/Archives-of-Support-Questions/when-need-to-set-Block-replication-to-1/m-p/207474#M74051 <P>we get the following in spark logs</P><PRE>java.io.IOException: Failed to replace a bad datanode on the existing pipeline due to no more good datanodes being available to try. (Nodes: current=[DatanodeInfoWithStorage DatanodeInfoWithStorage\ The current failed datanode replacement policy is DEFAULT, and a client may configure this via 'dfs.client.block.write.replace-datanode-on-failure.policy' in its configuration. at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.findNewDatanode(DFSOutputStream.java:1036) </PRE><P>my ambari cluster include only 3 workers machines and each worker have only one data disk</P><P>I search in google and find solution can be about:</P><P>Block replication need to be set as 1 instead of 3 ( HDFS )</P><P>is it true ?</P><P>second - because my worker machine have obnly one data disk is it can be part of the problem ?</P><P><EM><STRONG>Block replication</STRONG> = The total number of files in the file system will be what's specified in the dfs.replication factor setting dfs.replication=1, means will be only one copy of the file in the file system.</EM></P> Wed, 31 Jan 2018 00:53:14 GMT mike_bronson7 2018-01-31T00:53:14Z https://community.cloudera.com/t5/Archives-of-Support-Questions/when-need-to-set-Block-replication-to-1/m-p/207474#M74051 <P>we get the following in spark logs</P><PRE>java.io.IOException: Failed to replace a bad datanode on the existing pipeline due to no more good datanodes being available to try. (Nodes: current=[DatanodeInfoWithStorage DatanodeInfoWithStorage\ The current failed datanode replacement policy is DEFAULT, and a client may configure this via 'dfs.client.block.write.replace-datanode-on-failure.policy' in its configuration. at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.findNewDatanode(DFSOutputStream.java:1036) </PRE><P>my ambari cluster include only 3 workers machines and each worker have only one data disk</P><P>I search in google and find solution can be about:</P><P>Block replication need to be set as 1 instead of 3 ( HDFS )</P><P>is it true ?</P><P>second - because my worker machine have obnly one data disk is it can be part of the problem ?</P><P><EM><STRONG>Block replication</STRONG> = The total number of files in the file system will be what's specified in the dfs.replication factor setting dfs.replication=1, means will be only one copy of the file in the file system.</EM></P> Wed, 31 Jan 2018 00:53:14 GMT https://community.cloudera.com/t5/Archives-of-Support-Questions/when-need-to-set-Block-replication-to-1/m-p/207474#M74051 mike_bronson7 2018-01-31T00:53:14Z https://community.cloudera.com/t5/Archives-of-Support-Questions/when-need-to-set-Block-replication-to-1/m-p/207475#M74052 <P>1. Block replication if for redundancy of data which ensures data is not lost due to bad disk or node going down. <BR />2. Replication 1 is set in situation when data can recreated at any point of time, the loss of data is not crucial. Like a job chain, output of one job is consumed by others and ebntually all intermediate data needs to be deleted. The intermediate data can be marked for Replication of 1 ( Still its good to have 2 ) <BR />3. Replication factor of 1 makes the cluster fault tolerant. <BR /><BR />In you case you have 3 worker node, RF of 1 means if a worker is bad, you loose data and the it cant be processed. <BR />I suggest you to use at RF=2 if you are concerned about space utilization. </P> Fri, 02 Feb 2018 23:46:42 GMT https://community.cloudera.com/t5/Archives-of-Support-Questions/when-need-to-set-Block-replication-to-1/m-p/207475#M74052 kgautam 2018-02-02T23:46:42Z