I have done some searches on this topic, and it seems that almost everyone recommend to use a copy of PROD environment to do such tests
For example this answer on SQA: click and also I've reviewed Microsoft's Performance Testing Guidance for Web Applications and some other resources.
and I actually know that testing on scaled down enviroment has a little value.
But in our case this is not an option- our Boss roundly said that we can't afford for a copy of PROD, and we must use much smaller testing environments to do performance tests.
I am looking for an information how to plan and organize such test in a sensible way ? What kind of tests we need to implement ? What data/metric we should collect ? What kind of problems can be/ or cannot be catch by this "reduced" test ?
Our PROD environment consists of 6 application servers, 2 database servers and a few auxiliary servers, the whole system supports about 200-400 simultanous users (on average).
Test environments are much smaller.