Writing to HDFS could only be replicated to 0 nodes instead of minReplication (=1)

Question

I have 3 data nodes running, while running a job i am getting the following given below error ,

java.io.IOException: File /user/ashsshar/olhcache/loaderMap9b663bd9 could only be replicated to 0 nodes instead of minReplication (=1). There are 3 datanode(s) running and 3 node(s) are excluded in this operation. at org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.chooseTarget(BlockManager.java:1325)

This error mainly comes when our DataNode instances have ran out of space or if DataNodes are not running. I tried restarting the DataNodes but still getting the same error.

dfsadmin -reports at my cluster nodes clearly shows a lots of space is available.

I am not sure why this is happending.

Answer 1

1.Stop all Hadoop daemons

for x in `cd /etc/init.d ; ls hadoop*` ; do sudo service $x stop ; done 

2.Remove all files from /var/lib/hadoop-hdfs/cache/hdfs/dfs/name

Eg: devan@Devan-PC:~$ sudo rm -r /var/lib/hadoop-hdfs/cache/ 

3.Format Namenode

sudo -u hdfs hdfs namenode -format 

4.Start all Hadoop daemons

for x in `cd /etc/init.d ; ls hadoop*` ; do sudo service $x start ; done 

Stop All Hadoop Service