Agreed here. Whenever you have id disagreement between NN and DN. Simply, delete all the entries in your df/data directory and restart DN. No need to reformat NN.
Rgds, AK47 From: shashwat shriparv [mailto:[email protected]] Sent: Friday, November 16, 2012 2:53 AM To: [email protected] Subject: Re: High Availability - second namenode (master2) issue: Incompatible namespaceIDs Delete the VERSION for the datanode before format. ∞ Shashwat Shriparv On Fri, Nov 16, 2012 at 1:15 PM, hadoop hive <[email protected]<mailto:[email protected]>> wrote: Seems like you havn't format your cluster (if its 1st time made). On Fri, Nov 16, 2012 at 9:58 AM, [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> wrote: Hi, Please help! I have installed a Hadoop Cluster with a single master (master1) and have HBase running on the HDFS. Now I am setting up the second master (master2) in order to form HA. When I used JPS to check the cluster, I found : 2782 Jps 2126 NameNode 2720 SecondaryNameNode i.e. The datanode on this server could not be started In the log file, found: 2012-11-16 10:28:44,851 ERROR org.apache.hadoop.hdfs.server.datanode.DataNode: java.io.IOException: Incompatible namespaceIDs in /app/hadoop/tmp/dfs/data: namenode namespaceID = 1356148070<tel:1356148070>; datanode namespaceID = 1151604993<tel:1151604993> One of the possible solutions to fix this issue is to: stop the cluster, reformat the NameNode, restart the cluster. QUESTION: As I already have HBASE running on the cluster, if I reformat the NameNode, do I need to reinstall the entire HBASE? I don't mind to have all data lost as I don't have many data in HBASE and HDFS, however I don't want to re-install HBASE again. On the other hand, I have tried another solution: stop the DataNode, edit the namespaceID in current/VERSION (i.e. set namespaceID=1151604993<tel:1151604993>), restart the datanode, it doesn't work: Warning: $HADOOP_HOME is deprecated. starting master2, logging to /usr/local/hadoop-1.0.4/libexec/../logs/hadoop-hduser-master2-master2.out Exception in thread "main" java.lang.NoClassDefFoundError: master2 Caused by: java.lang.ClassNotFoundException: master2 at java.net.URLClassLoader$1.run(URLClassLoader.java:202) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:190) at java.lang.ClassLoader.loadClass(ClassLoader.java:306) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:247) Could not find the main class: master2. Program will exit. QUESTION: Any other solutions? Thanks NOTICE: This e-mail message and any attachments are confidential, subject to copyright and may be privileged. Any unauthorized use, copying or disclosure is prohibited. If you are not the intended recipient, please delete and contact the sender immediately. Please consider the environment before printing this e-mail. AVIS : le présent courriel et toute pièce jointe qui l'accompagne sont confidentiels, protégés par le droit d'auteur et peuvent être couverts par le secret professionnel. Toute utilisation, copie ou divulgation non autorisée est interdite. Si vous n'êtes pas le destinataire prévu de ce courriel, supprimez-le et contactez immédiatement l'expéditeur. Veuillez penser à l'environnement avant d'imprimer le présent courriel
