(Answering beyond Uma's reply) > Can a DN also act as SNN, any pros and cons of having this configuration ?
You can run SNN on a regular slave box if you can't have a dedicate a box, it shouldn't be an issue for small clusters -- Do ensure its disk configuration is proper, and its allocated near to the same heap as the NameNode is. For large clusters where the fsimage and periodic edits file sizes are larger, it would be worth placing it on a separate box given SNN's interactions. On 26-Dec-2011, at 7:53 PM, Uma Maheswara Rao G wrote: > Hey Praveenesh, > > You can start secondary namenode also by just giving the option ./hadoop > secondarynamenode > > DN can not act as seconday namenode. The basic work for seconday namenode is > to do checkpointing and getting the edits insync with Namenode till last > checkpointing period. DN is to store the real data blocks physically. > you need to configure correct namenode http address also for the > secondaryNN, so that it can connect NN for checkpointing operations. > http://hadoop.apache.org/common/docs/current/hdfs_user_guide.html#Secondary+NameNode > You can configure secondary node IP in masters file, start-dfs.sh itself will > start the SNN automatically as it starts DN and NN as well. > > also you can see > http://www.cloudera.com/blog/2009/02/multi-host-secondarynamenode-configuration/ > > Regards, > Uma > ________________________________________ > From: praveenesh kumar [[email protected]] > Sent: Monday, December 26, 2011 5:05 PM > To: [email protected] > Subject: Secondary Namenode on hadoop 0.20.205 ? > > Hey people, > > How can we setup another machine in the cluster as Secondary Namenode > in hadoop 0.20.205 ? > Can a DN also act as SNN, any pros and cons of having this configuration ? > > Thanks, > Praveenesh
