Apache Hadoop HDFS errors

The Hadoop Distributed File System (HDFS) is a distributed file system designed to run on commodity hardware

https://hadoop.apache.org/docs/r1.2.1/hdfs_design.html
Solution coverage:
Summary coverage:

Nothing to list here.
Package nameClass namePatterns foundSolution coverageSummary coverage
org.apache.hadoop.hdfs.server.namenodeFSNamesystem73
org.apache.hadoop.hdfs.server.namenodeNameNode54
org.apache.hadoop.hdfs.server.namenodeNameNodeRpcServer19
org.apache.hadoop.hdfs.server.namenodeFSPermissionChecker16
org.apache.hadoop.hdfs.server.namenodeFSImage9
org.apache.hadoop.hdfs.server.namenodeSecondaryNameNode7
org.apache.hadoop.hdfs.server.namenodeFSDirectory7
org.apache.hadoop.hdfs.server.namenodeFSEditLog5
org.apache.hadoop.hdfs.server.namenodeINodeFile4
org.apache.hadoop.hdfs.server.namenodeEditLogOutputStream1
org.apache.hadoop.hdfs.server.namenodeFSDirAttrOp1
org.apache.hadoop.hdfs.server.namenodeSecondaryNameNode$21
org.apache.hadoop.hdfs.server.namenodeFileJournalManager1
org.apache.hadoop.hdfs.server.namenodeMetaRecoveryContext1
org.apache.hadoop.hdfs.server.namenodeTransferFsImage1
org.apache.hadoop.hdfs.server.namenodeNNStorage1
org.apache.hadoop.hdfs.server.namenodeJournalSet$JournalAndStream1
Package nameClass nameMethod namePatterns foundSolution coverage
org.apache.hadoop.hdfs.server.namenodeNameNodeRpcServeraddBlock7
org.apache.hadoop.hdfs.server.namenodeNameNodeRpcServergetBlockLocations5
org.apache.hadoop.hdfs.server.namenodeNameNodeRpcServermkdirs3
org.apache.hadoop.hdfs.server.namenodeNameNodeRpcServergetAdditionalDatanode1
org.apache.hadoop.hdfs.server.namenodeNameNodeRpcServerregisterDatanode1
org.apache.hadoop.hdfs.server.namenodeNameNodeRpcServercheckNNStartup1
org.apache.hadoop.hdfs.server.namenodeNameNodeRpcServerrollEditLog1
Package nameClass nameMethod nameException TypePatterns foundSolution coverage
org.apache.hadoop.hdfs.server.namenodeNameNodeRpcServeraddBlockDFSClient3
org.apache.hadoop.hdfs.server.namenodeNameNodeRpcServeraddBlockIOException2
org.apache.hadoop.hdfs.server.namenodeNameNodeRpcServeraddBlockDataStreamer1
org.apache.hadoop.hdfs.server.namenodeNameNodeRpcServeraddBlockTaskSetManager1