I am getting this error in one or two nodes in a hadoop cluster where rest of the nodes are running fine:
ERROR org.apache.hadoop.hdfs.server.datanode.DataNode: java.io.IOException: ***** Upgrade is not supported from this older version of storage to the current version. Please upgrade to Hadoop-0.14 or a later version and then upgrade to current version. Old layout version is 'too old' and latest layout version this software version can upgrade from is -7.
Any idea how to fix this prob. without losing the data.