Resource-Efficient Replication and Migration of Virtual Machines.

Continuous replication and live migration of Virtual Machines (VMs) are two vital tools in a virtualized environment, but they are resource-expensive. Continuously replicating a VM's checkpointed state to a backup host maintains high-availability (HA) of the VM despite host failures, but checkpoint replication can generate significant network traffic. Each replicated VM also incurs a 100% memory overhead, since the backup unproductively reserves the same amount of memory to hold the redundant VM state. Live migration, though being widely used for load-balancing, power-saving, etc., can also generate excessive network traffic, by transferring VM state iteratively. In addition, it can incur a long completion time and degrade application performance. This thesis explores ways to replicate VMs for HA using resources efficiently, and to migrate VMs fast, with minimal execution disruption and using resources efficiently. First, we investigate the tradeoffs in using different compression methods to reduce the network traffic of checkpoint replication in a HA system. We evaluate gzip, delta and similarity compressions based on metrics that are specifically important in a HA system, and then suggest guidelines for their selection. Next, we propose HydraVM, a storage-based HA approach that eliminates the unproductive memory reservation made in backup hosts. HydraVM maintains a recent image of a protected VM in a shared storage by taking and consolidating incremental VM checkpoints. When a failure occurs, HydraVM quickly resumes the execution of a failed VM by loading a small amount of essential VM state from the storage. As the VM executes, the VM state not yet loaded is supplied on-demand. Finally, we propose application-assisted live migration, which skips transfer of VM memory that need not be migrated to execute running applications at the destination. We develop a generic framework for the proposed approach, and then use the framework to build JAVMM, a system that migrates VMs running Java applications skipping transfer of garbage in Java memory. Our evaluation results show that compared to Xen live migration, which is agnostic of running applications, JAVMM can reduce the completion time, network traffic and application downtime caused by Java VM migration, all by up to over 90%.PhDComputer Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/111575/1/karenhou_1.pd

A Complementary Third Law for Black Hole Thermodynamics

There are some examples in the literature, in which despite the fact that the underlying theory or model does not impose a lower bound on the size of black holes, the final temperature under Hawking evaporation is nevertheless finite and nonzero. We show that under some loose conditions, the black hole is necessarily an effective remnant, in the sense that its evaporation time is infinite. That is, the final state that there is nonzero finite temperature despite having no black hole remaining cannot be realized. We discuss the limitations, subtleties, and the implications of this result, which is reminiscent of the third law of black hole thermodynamics, but with the roles of temperature and size interchanged. We therefore refer to our result as the "complementary third law" for black hole thermodynamics.Comment: 10 pages, 5 figures; improved and published versio

The Relationship between Flow Experience in Leisure and Life Satisfaction in Undergraduates

Objective: To understand the current situation of undergraduates' flow experience in leisure and life satisfaction, and to explore the relationship between the two. Methods: A stratified random sampling method was used to select 781 undergraduates (377 males and 410 females) from 7 colleges and universities in Guangdong Province. They were investigated using the Flow Experience in Leisure Questionnaire (FELQ) and the Youth Life Satisfaction Scale (YLSS). Results: The total scores of FELQ and YLSS of the students in this group are (161.73 ± 19.81) and (174.45 ± 26.50). FELQ's unity of knowledge and action, challenge and skill balance, concentration, grade ranking, family economic status are positively related to YLSS 'life satisfaction (β = .227, .115, .098, .158, .082, P < .05); "Like to sleep during leisure" is negatively correlated with life satisfaction of YLSS (β =-. 097, P <.05); FELQ's unity of knowledge and action, concentration, grade ranking and family economic status are positively related to YLSS's self-satisfaction (β = .286, .126, .194, .096, P <.01); "Like to sleep during leisure” is negatively correlated with YLSS ’s self-satisfaction (β =-. 091, P <.01); FELQ ’s unity of knowledge and action, challenge and skill balance, father’s occupation, “like self-study in leisure” are positively related to YLSS ’environmental satisfaction (β = .198, .131, .075, .073, P <.05); "Like to sleep during leisure", gender and YLSS environment satisfaction negatively correlated (β =-. 094, -.091, P <.01). Conclusion: Flow experience in leisure, types of leisure activities, gender, grade ranking and family factors (family economic status and father's occupation) may be related factors for the development of college students' life satisfaction

Leading Effect of CP Violation with Four Generations

In the Standard Model with a fourth generation of quarks, we study the relation between the Jarlskog invariants and the triangle areas in the 4-by-4 CKM matrix. To identify the leading effects that may probe the CP violation in processes involving quarks, we invoke small mass and small angle expansions, and show that these leading effects are enhanced considerably compared to the three generation case by the large masses of fourth generation quarks. We discuss the leading effect in several cases, in particular the possibility of large CP violation in $b \to s$ processes, which echoes the heightened recent interest because of experimental hints.Comment: 12 pages, no figur