最新文档-Live Migration of Virtual Machines

发布于:2021-06-19 14:57:18

Live Migration of Virtual Machines
Christopher Clark, Keir Fraser, Steven Hand, Jacob Gorm Hansen, Eric Jul, Christian Limpach, Ian Pratt, Andrew Warfield
University of Cambridge Computer Laboratory, Department of Computer Science University of Copenhagen
Presentation by Marty Krogel

Outline
Goal Why VM migration? Related works Design Choices
Implementation Handling Local Resources Design Overview Testing the Implementation Benchmarks Future Work Conclusion

Goal
To find a quick and efficient way to transfer services between physical servers.

Challenges
Minimizing downtime. Keeping total migration time down. Avoid disrupting active services.

Benefits of Migrating Virtual Machines Instead of Processes
Avoids 'residual dependencies'. Can transfer in-memory state information. Allows separation of concern between users and operator of a data center or cluster.

Related Work
The Collective project Zap NomadBIOS VMotion Process migration
Sprite, MOSIX Java and .NET even suffer

Memory Migration Options
Push phase Stop-and-copy phase Pull phase

Implementation
Pre-copy migration
Bounded iterative push phase
Rounds Writable Working Set
Short stop-and-copy phase
Careful to avoid service degradation

Handling Local Resouces
Open network connections
Migrating VM can keep IP and MAC address. Broadcasts ARP new routing information
Some routers might ignore to prevent spoofing A guest OS aware of migration can avoid this problem
Local storage
Network Attached Storage

Design Overview

Tracking Writable Working Set
Xen inserts shadow pages under the guest OS, populated using guest OS's page tables.
The shadow pages are marked read-only. If OS tries to write to a page, the resulting page
fault is trapped by Xen. Xen checks the OS's original page table and
forwards the appropriate write permission. If the page is not read-only in the OS's PTE,
Xen marks the page as dirty.

Writable Working Set

Linux Kernel Compile

OLTP Database

Quake 3

SPECweb

Implementation Issues
Managed Migration vs. Self Migration Dynamic Rate-Limiting Rapid Page Dirtying Paravirtualized Optimizations
Stunning Rogue Processes Freeing Page Cache Pages

Stunning Rogue Process

Test Setup
2 Dell PE-2650 server-class machines Dual Xeon 2GHz CPUs
Only used 1 CPU HyperThreading enabled
2GB Memory Broadcom TG3 network interface Gigabit Ethernet switch NetApp F840 Network attached storage server using iSCSI
protocol XenLinux 2.4.27 OS

Simple Web Server

Complex Web Workload: SPECweb99

Low-Latency Server: Quake 3

Diabolical Workload: MMuncher

Conclusion
By integrating live OS migration into the Xen virtual machine monitor, rapid movement of interactive workload across a cluster or data center is possible. Using pre-copying and dynamically adapting network-bandwith total downtime can be reduced to imperceptible levels, even for complex interactive services.

Future Work
Cluster Management Wide Area Network Redirection Migrating Block Devices

Questions?


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