Hi Steve, Thank you for your reply.
> no, it's the Namenode and JobTracker that needs to be restarted; > they are the bits that care where the boxes are. I confirmed it in my cluster, and I understood it as follows. First, the resolved node information is recorded in ConcurrentHashMap. Next same node toplogy decision, HashMap data is given priority to over a script. The HashMap data become invalid by restart of NameNode and JobTracker. Regards, Shinichi 2012/10/9 Steve Loughran <ste...@hortonworks.com> > > > On 8 October 2012 14:23, Shinichi Yamashita <shin1...@gmail.com> wrote: > >> Hi, >> >> I know that DataNode and TaskTracker must restart to change topology. >> > > no, it's the Namenode and JobTracker that needs to be restarted; they are > the bits that care where the boxes are. > > >> Is there the method to execute the topology change without restart of >> DataNode and TaskTracker? >> In other words, can I change the topology by a command? >> > > No -the map gets cached, and when the services start up they do quick > check to see if the topology is flat or spread across switches -and use > that flag to make various placement decisions. > > steve > > >
