Life cycle maintenance cost must be predicted for any new product. Correct management practice then requires the prediction to be checked by measurement, so that planning and budgets can be adjusted. This requires knowledge of the nature of the market, quality of the product and activities of the service organisation, and how they mutually interact. This paper describes this interaction, and the problems of data collection peculiar to each of the three areas. A relational database structure is defined to enforce consistency on the data. Particular attention is paid to the problems of having different copies of the software in different states of repair, having several versions of several products in use simultaneously, and recording running time in order to be able to measure reliability.