QoS-aware Storage Virtualization: A Framework for Multi-tier Infrastructures in Cloud Storage Systems

The emergence of the relatively modern phenomenon of cloud computing has manifested a different approach to the availability and storage of software and data on a remote online server ‘in the cloud’, which can be accessed by pre-determined users through the Internet, even allowing sharing of data in certain scenarios. Data availability, reliability, and access performance are three important factors that need to be taken into consideration by cloud providers when designing a high-performance storage system for any organization. Due to the high costs of maintaining and managing multiple local storage systems, it is now considered more applicable to design a virtualized multi-tier storage infrastructure, yet, the existing Quality of Service (QoS) must be guaranteed on the application level within the cloud without ongoing human intervention. Such interference seems necessary since the delivered QoS can vary widely both across and within storage tiers, depending on the access profile of the data. This survey paper encompasses a general framework for the optimal design of a distributed system in order to attain efficient data availability and reliability. To this extent, numerous state-of-the-art technologies and methods have been revised, especially for multi-tiered distributed cloud systems. Moreover, several critical aspects that must be taken into consideration for getting optimal performance of QoS-aware cloud systems are discussed, highlighting some solutions to handle failure situations, and the possible advantages and benefits of QoS. Finally, this papers attempts to argue the possible improvements that have been developed on QoS-aware cloud systems like Q-cloud since 2010, such as any extra attempts been carried forward to make the Q-cloud more adaptable and secure