I tried to do rolling upgrade from hadoop 2.5.2 to hadoop 2.7.2. As per reference <http://hadoop.apache.org/docs/current/hadoop-project-dist/hadoop-hdfs/HdfsRollingUpgrade.html#Rollback> one can rollback to previous release provided the finalize step is not done.
I upgraded the setup, did not finalize the upgrade and tried to rollback HDFS to 2.5.2 version. Facing following exception after starting *Name node 1* as Active with the “*-rollingUpgrade rollback*” option. *org.apache.hadoop.hdfs.server.common.IncorrectVersionException: Unexpected version of storage directory ..\Metadata\data\dfs\namenode. Reported: -63. Expecting = -57.* Faced similar exception when I started *Data node* based on Downgrade <http://hadoop.apache.org/docs/current/hadoop-project-dist/hadoop-hdfs/HdfsRollingUpgrade.html#Downgrade> approach also. *org.apache.hadoop.hdfs.server.common.IncorrectVersionException: Unexpected version of storage directory ..\Metadata\data\dfs\datanode. Reported: -56. Expecting = -55.* There is already a task regarding this but its in Open status. https://issues.apache.org/jira/browse/HDFS-9096 Is this known issue? Please let me know are there any other steps to perform rollback (from rolling upgrade) or is it not supported to rollback to Hadoop 2.5.2. Thanks, Dinesh Kumar P
