1. Live migration of Virtual Machines Nour Stefan, SCPD

2. Introduction Related work Design Writable Working Sets Implementation Issues Evaluation Future work Conclusions

3. Introduction OS virtualization – Data centers – Cluster computing Live OS migration – Avoid problem of residual dependencies – In-memory state can be transferred in a consistent and efficient way Kernel-internal state Application-level state – Separation of concerns between Users and Operator of a data center or cluster – Separation of hardware and software considerations, and consolidating clustered hardware into a single coherent management domain High-performance migration support for Xen

4. Related work Collective project – For slow connections and longer time spans – Stop the OS execution while transfer Zap NomadBIOS – Pre-copy migration – Not adapting to the writable working set

5. Design Migrating memory Balancing Downtime and Total migration time – Push phase – Stop-and-copy phase – Pull phase Local resources – Connections to local devices(disks, network interfaces) – Single switched LAN – Generate an unsolicited ARP reply from migrated host, advertising that the IP has moved to a new location – Network-Attached Storage

7. Writable Working Sets

8. Measuring Writable Working Sets

14. Implementation Issues Managed migration – Performed largely outside the migratee – Migration daemons running in the management VM of the source and destination (new VM on destination) – Rounds of copying (dirtied during the previous round) – Dirty bitmap copied from Xen at start of each round – Shadow page tables (read-only page-tables entries => page fault trapped by Xen)

15. Implementation Issues Self migration – Implemented within the migratee OS – Migration stub on destination machine – Consistent OS checkpointing Two-stage stop-and-copy phase – Disables all OS activity except for migration => final scan of dirty bitmap => shadow buffer Transfer shadow buffer

16. Implementation Issues Dynamic Rate-Limiting Rapid Page Dirtying

17. Evaluation Test setup – Dual Intel Xeon 2GHz CPU and 2GB memory – TG3 broadband

18. Evaluation

22. Future work Cluster management Wide Area Network redirection Migrating Block Devices

23. Conclusions By integrating live OS migration into the Xen virtual machine monitor we enable rapid movement of interactive workloads within clusters and data centers. Our dynamic network-bandwidth adaptation allows migration to proceed with minimal impact on running services, while reducing total downtime to below discernable thresholds. Our comprehensive evaluation shows that realistic server workloads such as SPECweb99 can be migrated with just 210ms downtime, while a Quake3 game server is migrated with an imperceptible 60ms outage.

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