Extrapolation

[vin...@gmail.com]

Hi All

I did my load test in UAT enviroment.Now the users are asking me to
extrapolate the result and say for
the production environment.

I want to know the details on the extrapolation.Can any one provide me
with extrapolation details and how to proceed on that?

Regards
Vinod

[Gaz Davidson]

First work out how the different system counters look with different
numbers of virtual users, servers, and so on. Plot these on a graph,
then extrapolate like you would in simple mathematics.
http://en.wikipedia.org/wiki/Extrapolation

This is only useful for transaction response times and system
counters, it *cannot* show where you will reach hard limits within the
infrastructure. It is a useful technique when showing that a system is
unlikely to work, but it can't provide any assurance that it will
work! To extrapolate with any degree of accuracy you need to
understand system performance completely, like when you have
statistics from production and can compare them to a smaller test
environment.

So be very, very careful when doing this.

[Roland Jefferson JR]

Vinod,

Extrapolation, is more of capacity planning and thier are many models for this.

you need to compare your hardware cpu and memory power to production. 

And run your tests on 1 bank of servers and extrapolate up, based on what that bank of severs can handle and when you reach the breaking points in your application.  

Multiply out, by the increase in number of servers in production for a start.

next, you need to look at the size and clusterirng of your Db and if your qa environment is even close to production. this is a whole nother issue.

Best of luck,

Roland