On Thu, Jun 24, 2010 at 8:20 AM, Jeff Whiting <je...@qualtrics.com> wrote:
> 1) You have to start and restart > 2) Yes that is how it would get the new directory. However changing the > directory means it wont be able to find any of your old data. If you don't > want to start over from scratch you will want to stop dfs then copy the > files over to the new data directory and then restart it. > what about I simply add additional directory? i.e., leave the previous one in the list. will that make the old data lost? From: ------------------- dfs.data.dir /opt/hadoop/data -------------------- To: ------------------- dfs.data.dir /opt/hadoop/data, /home/sean/hadoopdata -------------------- > 3) Doing the namenode -format will clean up the directory on the name node > and make everything good to go with no data in dfs. However you'll have to > go to the datanodes and clean out their data directories. If you leave > data in the directory on the datanodes they will be unable to join with the > namenode. > > This isn't the most technical explanation but hopefully it helps. > ~Jeff > > > Sean Bigdatafun wrote: > >> Can someone tell me what "hadoop namenode -format" does under the hood? >> >> I have started my HDFS cell with the following configuration. >> ------------------- >> dfs.data.dir >> /opt/hadoop/data >> -------------------- >> >> Overtime, I want to add another directory as the data.dir, how can I >> achieve it? >> 1) Can I simply edit "dfs.data.dir" in the hdfs-site.xml without stopping >> my cell? >> >> 2) If 1) is not legitimate, can I run "stop-dfs.sh", then do 1) and then >> "start-dfs.sh"? >> >> 3) My last question here is what "hadoop namenode -format" does. If I run >> it on my Namenode, does it clean up the data.dir? and do I need to manually >> clean up the data.dir on Datanode? >> >> Thanks, >> Sean >> >> >> >> >> >> > -- > Jeff Whiting > Qualtrics Senior Software Engineer > je...@qualtrics.com > >