Dependability Differentiation in Cloud Services

As cloud computing is becoming more mature and pervasive, almost all types of services are being deployed in clouds. This has also widened the spectrum of cloud users which encompasses from domestic users to large companies. One of the main concerns of large companies outsourcing their IT functions to clouds is the availability of their functions. On the other hand, availability requirements for domestic users are not very strict. This requires the cloud service providers to guarantee different dependability levels for different users and services. In this book, different types of services are identified and grouped together both according to their deployment nature and their target users. Also a range of techniques for guaranteeing dependability in the cloud environment are identified and classified. In order to quantify dependability provided by different techniques, a cloud system is modeled. Two different levels of dependability differentiation, namely; differentiation depending upon the state of standby replica and differentiation depending upon the spatial separation of active and standby replicas are considered, modeled and studied.