  Virtualization has become commonplace in modern data centers, often referred
as "computing clouds". The capability of virtual machine live migration brings
benefits such as improved performance, manageability and fault tolerance, while
allowing workload movement with a short service downtime. However, service
levels of applications are likely to be negatively affected during a live
migration. For this reason, a better understanding of its effects on system
performance is desirable. In this paper, we evaluate the effects of live
migration of virtual machines on the performance of applications running inside
Xen VMs. Results show that, in most cases, migration overhead is acceptable but
cannot be disregarded, especially in systems where availability and
responsiveness are governed by strict Service Level Agreements. Despite that,
there is a high potential for live migration applicability in data centers
serving modernInternet applications. Our results are based on a workload
covering the domain of multi-tier Web 2.0 applications.
