Dynamic consolidation of virtual machines (VMs) through live migration is a promising technology for IaaS datacenters. VMs are dynamically packed onto fewer server nodes, thereby eliminating excessive power consumption. Existing studies on VM consolidation, however, are based on precopy live migration, which requires dozens of seconds to switch the execution hosts of VMs. It is difficult to optimize VM locations quickly on sudden load changes, resulting in serious violations of VM performance criteria. In this paper, we propose an advanced VM consolidation system exploiting postcopy live migration, which greatly alleviates performance degradation. VM locations are reactively optimized in response to ever-changing resource usage. Sudden overloading of server nodes are promptly resolved by quickly switching the execution hosts of VMs. We have developed a prototype of our consolidation system and evaluated its feasibility through experiments. Our results show that our consolidation system achieved a higher degree of performance assurance than using precopy migration. Performance degradation is 12% or less, even for memory-intensive workloads, which is less than half the level using precopy migration.

No abstract

No abstract

No abstract

No abstract

No abstract

No abstract

International audienceAs real systems become larger and more complex, the use of simulator frameworks grows in our research community. By leveraging them, users can focus on the major aspects of their algorithm, run in-siclo experiments (i.e., simulations), and thoroughly analyze results, even for a large-scale environment without facing the complexity of conducting in-vivo studies (i.e., on real testbeds). Since nowadays the virtual machine (VM) technology has become a fundamental building block of distributed computing environments, in particular in cloud infrastructures, our community needs a full-fledged simulation framework that enables us to investigate large-scale virtualized environments through accurate simulations. To be adopted, such a framework should provide easy-to-use APIs as well as accurate simulation results. In this paper, we present a highly-scalable and versatile simulation framework supporting VM environments. By leveraging SimGrid, a widely-used open-source simulation toolkit, our simulation framework allows users to launch hundreds of thousands of VMs on their simulation programs and control VMs in the same manner as in the real world (e.g., suspend/resume and migrate). Users can execute computation and communication tasks on physical machines (PMs) and VMs through the same SimGrid API, which will provide a seamless migration path to IaaS simulations for hundreds of SimGrid users. Moreover, SimGrid VM includes a live migration model implementing the precopy migration algorithm. This model correctly calculates the migration time as well as the migration traffic, taking account of resource contention caused by other computations and data exchanges within the whole system. This allows user to obtain accurate results of dynamic virtualized systems. We confirmed accuracy of both the VM and the live migration models by conducting several micro-benchmarks under various conditions. Finally, we conclude the article by presenting a first use-case of one consolidation algorithm dealing with a significant number of VMs/PMs. In addition to confirming the accuracy and scalability of our framework, this first scenario illustrates the main interest of SimGrid VM: investigating through in-siclo experiments pros/cons of new algorithms in order to limit expensive in-vivo experiments only to the most promising ones