Architectures and Algorithms for Resource Management in Virtualized Cloud Data Centers

Cloud Computing has raised a great interest over the last years as it represents an enabling technology for flexible and ubiquitous access over the network to a set of shared computing resources. Cloud paradigm leverages the instruments of the virtualization technique, such as the extit{VM Live Migration}, which can be exploited in order to achieve multiple objectives. For instance, it could be used for hardware maintenance purposes or to avoid over-load and under-load in the resources utilization. Another typical use of the VM migration is the consolidation of the workload into a smaller number of physical hosts: this is one of the techniques aimed at increasing the energy efficiency of the IT infrastructure, which represents the motivation behind the birth of the extit{Green Computing}. However, despite all the advantages that come from the application of the cloud paradigm, there is some reluctance in its adoption for mission critical infrastructures because of the security pitfalls it still exhibits, as well as the lack of mechanisms intended at increasing isolation and protection from internal and external threats. This thesis is intended at exploring both the described aspects: on one hand, an architecture for enhancing security of a virtualized critical infrastructure is designed and provided with a mitigation strategy based on the Software Defined Networking approach and live migration. On the other hand, migrations are used to propose two VM consolidation strategies with the objective of minimizing the overall infrastructure power consumption.