Abstract
Cloud Computing is emerging today as a service model used to relocate locally-based data and applications to virtualized services available via Internet at a lower cost. A key to exploit the benefits of this model is orchestration which consists in coordinating effectively the deployment of a set of virtualized services in order to fulfill operational and quality objectives of end users and Cloud providers. Cloud orchestration can be carried out at two levels: hardware level orchestration and software level orchestration. In this paper, we highlight the main challenging points about the Cloud orchestration concept. Then, we carry on a comparative study of some existing research works involved with this concept at hardware and software levels.