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Evaluation of delta compression techniques for efficient live migration of large virtual machines
Umeå University, Faculty of Science and Technology, Department of Computing Science. (UMIT)
SAP (UK) Limited, Belfast, United Kingdom.
Umeå University, Faculty of Science and Technology, Department of Computing Science. (UMIT)
Umeå University, Faculty of Science and Technology, Department of Computing Science. (UMIT)
2011 (English)In: The 2011 ACM SIGPLAN/SIGOPS International Conference on Virtual Execution Environments (VEE 2011), New York, NY: ACM Press, 2011, 111-120 p.Conference paper, Published paper (Refereed)
Abstract [en]

Despite the widespread support for live migration of Virtual Machines (VMs) in current hypervisors, these have significant shortcomings when it comes to migration of certain types of VMs. More specifically, with existing algorithms, there is a high risk of service interruption when migrating VMs with high workloads and/or over low-bandwidth networks. In these cases, VM memory pages are dirtied faster than they can be transferred over the network, which leads to extended migration downtime. In this contribution, we study the application of delta compression during the transfer of memory pages in order to increase migration throughput and thus reduce downtime. The delta compression live migration algorithm is implemented as a modification to the KVM hypervisor. Its performance is evaluated by migrating VMs running different type of workloads and the evaluation demonstrates a significant decrease in migration downtime in all test cases. In a benchmark scenario the downtime is reduced by a factor of 100. In another scenario a streaming video server is live migrated with no perceivable downtime to the clients while the picture is frozen for eight seconds using standard approaches. Finally, in an enterprise application scenario, the delta compression algorithm successfully live migrates a very large system that fails after migration using the standard algorithm. Finally, we discuss some general effects of delta compression on live migration and analyze when it is beneficial to use this technique.

Place, publisher, year, edition, pages
New York, NY: ACM Press, 2011. 111-120 p.
Series
ACM SIGPLAN Notices, ISSN 1523-2867 ; Vol. 46 Nr. 7
Keyword [en]
Virtualization, Live migration, Compression, Performance evaluation
National Category
Computer Science
Identifiers
URN: urn:nbn:se:umu:diva-40370DOI: 10.1145/2007477.1952698ISI: 000294949300011ISBN: 978-1-4503-0687-4 (print)OAI: oai:DiVA.org:umu-40370DiVA: diva2:399456
Conference
7th ACM SIGPLAN/SIGOPS international conference on Virtual execution environments
Available from: 2011-02-22 Created: 2011-02-22 Last updated: 2015-06-17Bibliographically approved
In thesis
1. Live VM Migration: Principles and Performance
Open this publication in new window or tab >>Live VM Migration: Principles and Performance
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Alternative title[sv]
Livemigrering av Virtuella Maskiner : Principer och Prestanda
Abstract [en]

Virtualization is a key technology for cloud computing as it allows several operating system instances to run on the same machine, enhances resource manageability and enables flexible definition of billing units. Virtualization works by adding a software layer, a hypervisor, on top of the hardware platform. Virtual Machines, \emph{VMs}, are run on top of the hypervisor, which provisions hardwares resources to the VM guests. In addition to enabling higher utilization of hardware resources, the ability to move VMs from one host to another is an important feature.

Live migration is the concept of migrating a VM while it is running and responding to requests. Since VMs can be re-located while running, live migration allows for better hardware utilization. This is because placement of services can be performed dynamically and not only when the are started. Live migration is also a useful tool for administrative purposes. If a server needs to be taken off-line for maintenance reasons, it can be cleared of services by live migrating these to other hosts.

This thesis investigates the principles behind live migration. The common live migration approaches in use today are evaluated and common objectives are presented as well as challenges that have to be overcome in order to implement an ideal live migration algorithm. The performance of common live migration approaches is also evaluated and it is found that even though live migration is supported by most hypervisors, it has drawbacks which makes the technique hard to use in certain situations. Migrating CPU and/or memory intensive VMs or migrating VMs over low-bandwidth links is a problem regardless of which approach that is used. To tackle this problem, two improvements to live migration are proposed and evaluated, delta compression and dynamic page transfer reordering. Both improvements demonstrate better performance than the standard algorithm when migrating CPU and/or memory intensive VMs and migrating over low bandwidth links. Finally, recommendations are made on which live migration approach to use depending on the scenario and also what improvements to the standard live migration algorithms should be used and when.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2012. 14 p.
Series
UMINF / Department of Computing Science, Umeå University, ISSN 0348-0542 ; 2012:12
Keyword
Live Migration, Virtualization
National Category
Computer Systems
Research subject
Computing Science
Identifiers
urn:nbn:se:umu:diva-87246 (URN)978-91-7459-452-2 (ISBN)
Presentation
2012-06-08, MIT-huset, MA121, Umeå universitet, Umeå, 16:10 (English)
Opponent
Supervisors
Available from: 2014-03-26 Created: 2014-03-25 Last updated: 2014-04-08Bibliographically approved
2. Dynamic Cloud Resource Management: Scheduling, Migration and Server Disaggregation
Open this publication in new window or tab >>Dynamic Cloud Resource Management: Scheduling, Migration and Server Disaggregation
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A key aspect of cloud computing is the promise of infinite, scalable resources, and that cloud services should scale up and down on demand. This thesis investigates methods for dynamic resource allocation and management of services in cloud datacenters, introducing new approaches as well as improvements to established technologies.Virtualization is a key technology for cloud computing as it allows several operating system instances to run on the same Physical Machine, PM, and cloud services normally consists of a number of Virtual Machines, VMs, that are hosted on PMs. In this thesis, a novel virtualization approach is presented. Instead of running each PM isolated, resources from multiple PMs in the datacenter are disaggregated and exposed to the VMs as pools of CPU, I/O and memory resources. VMs are provisioned by using the right amount of resources from each pool, thereby enabling both larger VMs than any single PM can host as well as VMs with tailor-made specifications for their application. Another important aspect of virtualization is live migration of VMs, which is the concept moving VMs between PMs without interruption in service. Live migration allows for better PM utilization and is also useful for administrative purposes. In the thesis, two improvements to the standard live migration algorithm are presented, delta compression and page transfer reordering. The improvements can reduce migration downtime, i.e., the time that the VM is unavailable, as well as the total migration time. Postcopy migration, where the VM is resumed on the destination before the memory content is transferred is also studied. Both userspace and in-kernel postcopy algorithms are evaluated in an in-depth study of live migration principles and performance.Efficient mapping of VMs onto PMs is a key problem for cloud providers as PM utilization directly impacts revenue. When services are accepted into a datacenter, a decision is made on which PM should host the service VMs. This thesis presents a general approach for service scheduling that allows for the same scheduling software to be used across multiple cloud architectures. A number of scheduling algorithms to optimize objectives like revenue or utilization are also studied. Finally, an approach for continuous datacenter consolidation is presented. As VM workloads fluctuate and server availability varies any initial mapping is bound to become suboptimal over time. The continuous datacenter consolidation approach adjusts this VM-to-PM mapping during operation based on combinations of management actions, like suspending/resuming PMs, live migrating VMs, and suspending/resuming VMs. Proof-of-concept software and a set of algorithms that allows cloud providers to continuously optimize their server resources are presented in the thesis.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2014. 26 p.
Series
Report / UMINF, ISSN 0348-0542 ; 2014:09
Keyword
Cloud computing, virtualization, distributed infrastructure, live migration, scheduling
National Category
Computer Science
Identifiers
urn:nbn:se:umu:diva-87904 (URN)978-91-7601-038-9 (ISBN)
Public defence
2014-05-06, Naturvetarhuset, N320, Umeå universitet, Umeå, 10:15 (English)
Opponent
Supervisors
Available from: 2014-04-15 Created: 2014-04-14 Last updated: 2014-04-14Bibliographically approved

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Svärd, PetterTordsson, JohanElmroth, Erik

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