The Challenge of Service Level Scalability for the Cloud

This paper presents a brief overview of the available literature on distributed systems scalability that serves as a justification for presenting some of the most prominent challenges that current Cloud systems need to face in order to deliver their pledged easy-to-use scalability. Through illustrative comparisons and examples, this paper aims to make the reader's acquaintance with this long needed problem in distributed systems: user-oriented service-level scalability. Scalability issues are analyzed from the Infrastructure as a Service IaaS and the Platform as a Service PaaS point of view, as they deal with different functions and abstraction levels. Next generation Cloud provisioning models rely on advanced monitoring and automatic scaling decision capabilities to ensure quality of service QoS, security and economic sustainability.