The links appeared outdated, I've updated those to reflect the current release 0.21's configurations. The configuration descriptions describe properly, the way to set them 'right'.
For 0.20 releases, only the configuration name changes: dfs.name.dir instead of dfs.namenode.name.dir, and dfs.data.dir instead of dfs.datanode.data.dir The value formatting remains the same. On Thu, Feb 10, 2011 at 11:18 PM, mike anderson <saidthero...@gmail.com> wrote: > Whew, glad I asked. > > It might be useful for someone to update the wiki: > http://wiki.apache.org/hadoop/FAQ#How_do_I_set_up_a_hadoop_node_to_use_multiple_volumes.3F > > -Mike > > On Thu, Feb 10, 2011 at 12:43 PM, Harsh J <qwertyman...@gmail.com> wrote: > >> DO NOT format your NameNode. Formatting a NameNode is equivalent to >> formatting a FS -- you're bound lose it all. >> >> And while messing with NameNode, after bringing it down safely, ALWAYS >> take a backup of the existing dfs.name.dir contents and preferably the >> SNN checkpoint directory contents too (if you're running it). >> >> The RIGHT way to add new directories to the NameNode's dfs.name.dir is >> by comma-separating them in the same value and NOT by adding two >> properties - that is not how Hadoop's configuration operates. In your >> case, bring NN down and edit conf as: >> >> > <property> >> > <name>dfs.name.dir</name> >> > <value>/mnt/hadoop/name,/public/hadoop/name</value> >> > </property> >> >> Create the new directory by copying the existing one. Both must have >> the SAME file and structure in them, like mirror copies of one >> another. Ensure that this new location, apart from being symmetric in >> content, is also symmetric in permissions. NameNode will require WRITE >> permissions via its user on all locations configured. >> >> Having configured properly and ensured that both storage directories >> mirror one another, launch your NameNode back up again (feel a little >> paranoid and do check namenode logs for any issues -- in which case >> your backup would be very essential as a requirement for recovery!). >> >> P.s. Hold on for a bit for a possible comment from another user before >> getting into action. I've added extra directories this way, but I do >> not know if this is "the" genuine way to do so - although it feels >> right to me. >> >> On Thu, Feb 10, 2011 at 10:27 PM, mike anderson <saidthero...@gmail.com> >> wrote: >> > This should be a straightforward question, but better safe than sorry. >> > >> > I wanted to add a second name node directory (on an NFS as a backup), so >> now >> > my hdfs-site.xml contains: >> > >> > <property> >> > <name>dfs.name.dir</name> >> > <value>/mnt/hadoop/name</value> >> > </property> >> > <property> >> > <name>dfs.name.dir</name> >> > <value>/public/hadoop/name</value> >> > </property> >> > >> > >> > When I go to start DFS i'm getting the exception: >> > >> > org.apache.hadoop.hdfs.server.common.InconsistentFSStateException: >> Directory >> > /public/hadoop/name is in an inconsistent state: storage directory does >> not >> > exist or is not accessible. >> > >> > >> > After googling a bit, it seems like I want to do "bin/hadoop namenode >> > -format" >> > >> > Is this right? As long as I shut down DFS before issuing the command I >> > shouldn't lose any data? >> > >> > Thanks in advance, >> > Mike >> > >> >> >> >> -- >> Harsh J >> www.harshj.com >> > -- Harsh J www.harshj.com
