Jun,
For testing purpose this might be ok. However as a rule if thumb you can run 2 processes per core. Hence if you are overloading then obviously the performance will degrade. On Aug 8, 2011 11:13 PM, "Arun C Murthy" <a...@hortonworks.com> wrote: > Jun, > > On Aug 8, 2011, at 2:19 AM, 谭军 wrote: >> 2 computers with 2 CPUs. >> Each CPU has 2 cores. >> Now I have 2 physical datanodes. >> Can I get 4 physical datanodes? >> I don't know wether I make my point clear? > > Running multiple datanodes on the same machine really doesn't buy you anything - the underlying storage is just partitioned. > > OTOH, if you just want to simulate a larger cluster you'll need to setup 2 different HADOOP_HOME, configs etc. and also need to ensure ports don't clash. Same for running multiple tasktrackers on same node - again, only makes sense while simulating. > > hth, > Arun >
