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SOLVED org apache hadoop hdfs server namenode SafeModeException Name node is in safe mode How to leave Namenode daemon in Hadoop Framework enters into safe mode in unusual situations. For example when disk is full, also in the start-up phase. You can see something like this. org.apache.hadoop.hdfs.server.namenode.SafeModeException: Cannot create directory /user/root/t. Name node is in safe mode So Hadoop needs to leave safemode. Running below command leaves safemode. bin/hadoop dfsadmin -safemode leave After doing the above command, Run  hadoop fsck  so that any inconsistencies crept in the hdfs might be sorted out. Use   hdfs   command instead of   hadoop  command for newer distributions: hdfs dfsadmin -safemode leave hadoop dfsadmin  has been deprecated, all hdfs related tasks are being moved to a separate command  hdfs. download file now

Storm java lang NoClassDefFoundError org apache curator RetryPolicy Recently I was working on a Trident topology with Trident-ML which uses nathan marzs storm-kafka which pushes the results from the Trident topology to be read by another storm topology. While the program works perfectly in local cluster testing. When it was deployed in a storm cluster, the following error showed up from nowhere: java.lang.NoClassDefFoundError: org/apache/curator/RetryPolicy The error got me stuck for more than half an hour, before i figured out a workable solution. It seems that i am using there is a version compatibility issues with the version of storm, trident-ml, and the storm-kafka. Originally i had been using the following dependencies in the pom file: <dependency> <groupId>org.apache.storm</groupId> <artifactId>storm-core</artifactId> <version>0.9.2-incubating</version> <scope>provided</scope> </dependency> <dependency> <groupI...