On 2/12/10 8:40 AM, Edson Ramiro wrote: > Hi all, > > I'm setting up a Hadoop Cluster and some doubts have > arisen about hadoop configuration. > > The Hadoop Cluster Setup [1] says that the mapred.system.dir must > be in the HDFS and be accessible from both the server and clients. > > Where is the HDFS directory? is the dfs.data.dir? > > should I export by NFS or other protocol the mapred.system.dir to > leave it accessible from server and clients? > > Thanks in advance > > [1] http://hadoop.apache.org/common/docs/current/cluster_setup.html > > Edson Ramiro >
Edson: An HDFS file system is a distributed global view controlled by the namenode. If a file is "in HDFS" all clients and servers that are pointed at the namenode will be able to see everything. This means that you don't need to do anything special to export or reveal the mapred.system.dir; that's what HDFS does. It's worth reading the HDFS Architecture paper on the Hadoop site or the Google GFS paper for details on how this all works and how it relates to map reduce. HTH. -- Eric Sammer [email protected] http://esammer.blogspot.com
