Formal Model To Reduce the Risk Of Cloud Outages

Abstract

Cloud outages have become very common in recent years as many companies adopt hosted services. One of the major reasons for cloud outages is the service level for availability, reliability, security not being met as mentioned in a service level agreement. The main purpose of this thesis is to introduce a model to calculate, control and reduce the risk of cloud outages. The objective is also to help consumers make an educated decision and to help them select a right providers. In order to understand the granularity of risk of cloud outage and its impact in the current cloud business, a survey was conducted to support our claim that there is a strong need to calculate the risk associated with a service before signing a service level agreement. Survey responses also helped to prioritize the service level parameters used in our model from the consumer point of view. Our model considers requirements, priorities, service level parameters, and cost as inputs. This model implements a modified version of a well-known mathematical model, Weighted Product Model (WPM) to compare different providers and to sort the eligible cloud providers. The methodology also uses Value At Risk (VAR) term, which is widely used term in the financial industry. The final output of the model, gives the risk value associated for a service for each parameter. Additionally, the model shows the probabilistic value for occurrence of cloud outage. The resulted information will be helpful for consumers to select a right cloud service provider with a minimum risk of cloud outage. This information will bring visibility of risk between a provider and a consumer helping to reduce the risk of cloud outage after the adoption of cloud service