The Benefits of Using Experimental Exploration for Cloud Migration Analysis and Planning Frank Fowley 1 , Divyaa Manimaran Elango 1 , Hany Magar 1 , and Claus Pahl 2(B ) 1 IC4, Dublin City University, Dublin 9, Ireland 2 SwSE, Free University of Bozen-Bolzano, Bolzano, Italy claus.pahl@unibz.it Abstract. Migration software systems to the cloud causes challenges. This applies especially for companies that do not have sufficient cloud expertise. In many of these companies there is a clear ideas about expected benefits. There is also an awareness of some potential problems. However, this is often not suf- ficient to assess the risks before starting on a full cloud migration of a legacy system. Technical and conceptual analyses can only help to identify risks in the migra- tion process with from a cost and a quality perspective to a limited extent. So, we investigate here the suitability of feasibility studies with a focus on experimental exploration. These studies would generally only cost 5% of the overall costs of a migration project, but can strongly support a reliable risk assessment. These can determine how much of the expectations and intentions can achieved in a cloud deployment. The cost of the migration, but also the cost of operating an IT sys- tem in the cloud can be estimated in the context of quality expectations. Using a feasibility study with an experimental core based on a partial prototype delivers much more reliable figures regarding configurations, quality-of-service and cost- ing than a theoretical analysis could deliver. We will embed our feasibility study approach into a pattern-based migration method. We report on a number of case studies to validate the expected benefits of feasibility-driven migration. Keywords: Cloud migration · Experiment · Prototyping · Migration patterns Cloud architecture · Cloud cost model · Performance · Scalability 1 Introduction Today, cloud computing is a widely used form of operating software. However, the migration of software systems to the cloud [2] is still a problem for many, especially small and medium-sized enterprises and organisations without sufficient cloud expertise [12]. These companies generally need to rely on support from consultants and solution providers. Expected benefits are known and an awareness of potential problems exists. However, this is often not sufficient to confidently embark on a full migration of a software system, which requires estimates of the migration costs as well as costs of operating software within the limits of required quality in the cloud. c  Springer International Publishing AG, part of Springer Nature 2018 D. Ferguson et al. (Eds.): CLOSER 2017, CCIS 864, pp. 157–176, 2018. https://doi.org/10.1007/978-3-319-94959-8_9