A difficult challenge that comes up regularly is the idea that performance assurance starts with Volume and Performance testing. The assertion is that unless detailed performance data for the solution is available then there is little that can usefully be done. I have touched on an alternative approach in my “Principles of Capacity Management” document, where I examine what can usefully be done at different project stages.
The difficulty is that early on in a project there is little that is well defined and known. The management of capacity and performance is considered to be a scientific discipline and so needs to be concerned with correct, hard and provable data. If the input information is anything less than ideal then the output result is incorrect – from a “garbage in, garbage out” principle.
My assertion is that this is analogous to stating that an organisation’s balance sheet must only contain correct data. The fact is that accountants use judgement to provide the figures on an organisation’s balance sheet. There are different methods, techniques and approaches to doing this – and the approach used needs to be “true and fair”. The figures do not represent an absolute truth, however, only a model. Modern organisations could not function effectively without these judgements.
Thus, my suggestion is that it is necessary to use appropriate judgement to build and calibrate a performance model early in a project. This judgement will turn out to be incorrect and so the assumptions, logic and estimates the model is built on should be documented. Thus, the process and results are open to scrutiny and discussion – which can be an opportunity for learning itself. Done well the resultant modelling should amply demonstrate its value during the course of a system’s lifecycle. If you need more detail please feel free to contact me at firstname.lastname@example.org, or call on +44 7887 536083.