You can decommission the datanode, and then un-decommission it. On Thu, May 14, 2009 at 7:44 AM, Alexandra Alecu <alexandra.al...@gmail.com>wrote:
> > Hi, > > I want to test how Hadoop and HBase are performing. I have a cluster with 1 > namenode and 4 datanodes. I use Hadoop 0.19.1 and HBase 0.19.2. > > I first ran a few tests when the 4 datanodes use local storage specified in > dfs.data.dir. > Now, I want to see what is the tradeoff if I switch from local storage to > network mounted storage (I know it sounds like a crazy idea but > unfortunately I have to explore this possibility). > > I would like to be able to change the dfs.data.dir and maybe in two steps > be > able to switch to the network mounted storage. > > What I had in mind was the following steps : > > 0. Assume initial status is a working cluster with local storage, e.g. > dfs.data.dir set to local_storage_path. > 1. Stop cluster: bin/stop-dfs > 2. Change dfs.data.dir by adding the network_storage_path to the local > storage_path. > 3. Start cluster: bin/start-dfs (this will format the new network > locations, > which is nice) > 4. <Perform some sort of directed balancing of all the data towards the > network storage location> > 5. Stop cluster: bin/stop-dfs > 6. Change dfs.data.dir parameter to only contain local_storage_path > 7. Start cluster and live happily ever after :-). > > The problem is , I don;t know if there is a command or an option to achieve > step 4. > Do you have any suggestions ? > > I found some info on how to add datanodes, but there is not much info on > how > to remove safely (without losing data etc) datanodes or storage locations > on > a particular node. > Is this possible? > > Many thanks, > Alexandra. > > > > > > -- > View this message in context: > http://www.nabble.com/How-to-replace-the-storage-on-a-datanode-without-formatting-the-namenode--tp23542127p23542127.html > Sent from the Hadoop core-user mailing list archive at Nabble.com. > > -- Alpha Chapters of my book on Hadoop are available http://www.apress.com/book/view/9781430219422 www.prohadoopbook.com a community for Hadoop Professionals
