Performance environment scaling and results extrapolation

In this article we shall discuss about the points we have to consider when we get a new environment or existing environment for performance testing.
Rule 1 - The configurations of Production and test env should match
eg - if they have 4 web, 2 app and 2 Db servers
test env might be 2 web, 1 app and 1 DB but not 1 web, 2 app, 1 Db etc....

Rule 2 - JVM heap memory should match
Prod 2 JVM with 4GB heap each
test has 1 JVM with 4 GB heap but not 1 JVM with 3GB
Rule 3 - The log settings of test and prod should match
Rule 4 - Check for the connection limits of all servers (limit should be w.r.to the performance tests we perform on that env)
Depending on the above responses and some more info specific to that env, we do the scaling.
Results extrapolation:-
Rule 2 is most important while doing extrapolation, as the available memory on that server is not important but the heap memory allocated is important and that is what we compare with production - not the total memory of server.

If you just have 1 JVM and have to extrapolate to prod with 4JVM's is not practical and results might not be accurate.

For accuracy we might need more than 1 JVM so that we can test with 1 JVM and then with 2 JVM's and then map the results to see the pattern and through curve fitting we can get a formula that can be used to extrapolate.

Note:- if you need more accuracy, you also need more samples
Apart from Rule 2, we also consider all the rules mentioned above to extrapolate the results.