  Moving existing legacy systems to cloud platforms is a difficult and high
cost process that may involve technical and non-technical resources and
challenges. There is evidence that the lack of understanding and preparedness
of cloud computing migration underpin many migration failures in achieving
organisations goals. The main goal of this article is to identify the most
important challenging activities for moving legacy systems to cloud platforms
from a perspective of reengineering process. Through a combination of a
bottom-up and a top-down analysis, a set of common activities is derived from
the extant cloud computing literature. These are expressed as a model and are
validated using a population of 104 shortlisted and randomly selected domain
experts from different industry sectors. We used a Web-based survey
questionnaire to collect data and analysed them using SPSS Sample T-Test. The
results of this study highlight the most important and critical challenges that
should be addressed by various roles within a legacy to cloud migration
endeavour. The study provides an overall understanding of this process
including common occurring activities, concerns and recommendations. In
addition, the findings of this study constitute a practical guide to conduct
this transition. This guide is platform agnostic and independent from any
specific migration scenario, cloud platform, or an application domain.
Keywords. Cloud Computing, Legacy Systems, Cloud Migration, Cloud Migration
Process
