Common errors and solutions for Hadoop deployment on Redhat Linux 5

Problems encountered:


1, execute command under Hadoop conf: hadoop-daemon.sh start Datanode cannot start Hadoop datanode:


[Hadoop@master conf]$ hadoop-daemon.sh start Datanode


Warning: $HADOOP _home is deprecated.


starting Datanode, logging to/opt/modules/hadoop/hadoop-1.1.2/libexec/. /logs/hadoop-hadoop-datanode-master.out


[Hadoop@master conf]$ JPS


4662 Namenode


4819 Jps


[Hadoop@master conf]$ tail-300f/opt/modules/hadoop/hadoop-1.1.2/libexec/. /logs/hadoop-hadoop-datanode-master.log


Error:


incompatible http://www.aliyun.com/zixun/aggregation/11696.html ">namespaceids In/data/hadoop/hdfs/data: Namenode Namespaceid = 573007068; Datanode Namespaceid = 1802250800


Workaround: Use the first online introduction: Delete the data directory (that is, the DFS.DATA.DIR directory configured in the Hdfs-site.xml file) and restart the Datanode.


[Hadoop@master conf]$ rm-rf/data/hadoop/hdfs/data


[Hadoop@master conf]$ ll/data/hadoop/hdfs/


Total 8


drwxrwxr-x 5 Hadoop hadoop 4096 June 6 08:17 name


drwxrwxr-x 2 Hadoop hadoop 4096 June 2 06:59 namesecondary


[Hadoop@master conf]$ hadoop-daemon.sh start Datanode


2, start jobtracker times wrong:


2013-07-06 10:03:09,584 INFO Org.apache.hadoop.mapred.JobTracker:problem Cleaning System Directory:hdfs://master : 9000/data/hadoop/mapred/mrsystem


org.apache.hadoop.ipc.RemoteException:java.io.FileNotFoundException:Parent path is not directory:/data


reason: There is a/data file (note is not a folder, and the parameters just don't match), can also be seen through the Web page:


namenode ' master:9000 '


Started:sat June 09:54:05 PDT 2013


version:1.1.2, r1440782


Compiled:thu 02:03:24 UTC 2013 by Hortonfo


Upgrades:there are no upgrades in progress.


Browse the filesystem


Namenode Logs


Workaround: Remove the change file: Hadoop fs-rmr/data that OK


3, compiling eclipse exported jar packages in Hadoop error:


[hadoop@master hadoop-1.1.2]$ hadoop jar Hdfs1.jar Com.hadoop.hdfs.HDFSMkdir


Warning: $HADOOP _home is deprecated.


Exception in thread "main" java.lang.unsupportedclassversionerror:com/hadoop/hdfs/hdfsmkdir:unsupported Major.minor version 51.0


Reason: The Java version used in Eclipse is inconsistent with the Java version used by Hadoop.


Workaround: Change the Java version in Eclipse to re-export the jar package.