Everything went fine , except the datanode when starting it , i got the exception below.
2014-12-15 15:28:53,734 INFO org.apache.hadoop.hdfs.server.common.Storage: Upgrading block pool storage directory /NAS/dfs/dn/current/BP-1056675496-10.15.101.22-1402685851165.
old LV = -55; old CTime = 0.
new LV = -56; new CTime = 1418674697177
2014-12-15 15:28:57,228 FATAL org.apache.hadoop.hdfs.server.datanode.DataNode: Initialization failed for Block pool <registering> (Datanode Uuid unassigned) service to Namenode/10.15.101.22:8022. Exiting.
java.io.IOException: EEXIST: File exists
To resolve this i manually have edited the VERSION on dfs directories and changed the ctime field and version fields to read and , replaced the namenode metadata backup that i have taken before upgrade.
Now when i bring up the cluster , i see namenode reports lot of blocks as missing, i tried to find out the blocks that were reported missing and i couldnt find it anywhere, please help to resolve this issue.
I cannot afford to wipe out everything on DN/NN dfs directories as the data in the cluster is heavily used.
The upgrade to v5.2 is not the same as in earlier minor version upgrades. There has been a version upgrade to HDFS metadata. Please undo the manual change to the Datanodes. Then follow this upgrade guide