Computation and Serving layer instances

[#1]

Must the computation and serving layer lie on the same instance?

If not, how do I tell the serving layer from which ip to take the data from?

Furthermore, can you please elaborate more on how to create multipe serving layers to improve scalability, and on how it improves performance if in fact they all have to lie on the same instance?

[#2 · Accepted solution]

No they do not. The serving layer must be able to access HDFS. It takes its config by default from Hadoop config on the local machine at /etc/hadoop/conf. If that is hard I can say more about how to directly specify the HDFS URL. For this reason you can run these on many different machines.