Gueyoung Jung

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Server consolidation based on virtualization is an important technique for improving power efficiency and resource utilization in cloud infrastructures. However, to ensure satisfactory performance on shared resources under changing application workloads, dynamic management of the resource pool via online adaptation is critical. The inherent tradeoffs(More)
Virtualization-based server consolidation is an important technique for cost and energy reductions in data center environments and a key enabler of cloud computing. However, to ensure adequate application isolation and performance, consolidation demands runtime resource reconfiguration, especially of multi-tier services that have dynamic, rapidly changing(More)
Creating good adaptation policies is critical to building complex autonomic systems since it is such policies that define the system configuration used in any given situation. While online approaches based on control theory and rule- based expert systems are possible solutions, each has its disadvantages. Here, a hybrid approach is described that uses(More)
A complex cloud application consists of virtual machines (VMs) running software such as web servers and load balancers, storage in the form of disk volumes, and network connections that enable communication between VMs and between VMs and disk volumes. The application is also associated with various requirements, including not only quantities such as the(More)
Traditional IT service-deployment technologies are based on scripts and configuration files, but their limited ability to express dependencies and verify configurations results in hard-to-use and erroneous system configurations. Emerging language- and model-based tools promise to address these deployment challenges, but their benefits aren't yet clearly(More)
Distributed applications typically interact with a number of heterogeneous and autonomous components that evolve independently. Methodical development of such applications can benefit from approaches based on domain-specific languages (DSLs). However, the evolution and customization of heterogeneous components introduces significant challenges to(More)
Virtual machine technology enables agile system deployments in which software components can be cheaply moved, replicated, and allocated hardware resources in a controlled fashion. This paper examines how these facilities can be used to provide enhanced solutions to the classic problem of ensuring high availability while maintaining performance. By(More)
IT today is driven by the trend of increasing scale and complexity. Utility and grid computing models, PlanetLab, and traditional data centers, are reaching the scale of thousands of computers. Installed software consists of dozens of interdependent applications and services. As the complexity and scale of these systems continues to grow, it becomes(More)
AbstractThe characterization of distributed n-tier application performance is an important and challenging problem due to their complex structure and the significant variations in their workload. Theoretical models have difficulties with such wide range of environmental and workload settings. Experimental approaches using manual scripts are error-prone,(More)