Virtualization ppt1
- 1. Virtual Machine and its Role in Distributed Systems
- 2. Virtualization • Virtualization deals with “extending or replacing an existing interface so as to mimic the behavior of another system” • Virtual system examples: virtual private network (VPN), virtual memory, virtual machine
- 9. • Run legacy software on non-legacy hardware • Run multiple operating systems on the same hardware • Create a manageable upgrade path • Manage outages (expected and unexpected) dynamically
- 10. • Reduce costs by consolidating services onto the fewest number of physical machines http://www.vmware.com/img/serverconsolidation.jpg
- 11. Non-virtualized Data Centers • Too many servers for too little work • High costs and infrastructure needs – Maintenance – Networking – Floor space – Cooling – Power – Disaster Recovery
- 12. Dynamic Data Center • Virtualization helps us break the “one service per server” model • Consolidate many services into a fewer number of machines when workload is low, reducing costs • Conversely, as demand for a particular service increases, we can shift more virtual machines to run that service • We can build a data center with fewer total resources, since resources are used as needed instead of being dedicated to single services
- 13. VM workload multiplexing – Multiplex VMs’ workload on the same group of physical servers • Aggregate multiple workload. Estimate total capacity need based on aggregated workload • Performance level of each VM be preserved Separate VM sizing VM multiplexing s1s2 s3 We expect s3 < s1 + s2. Benefit of multiplexing !
- 14. So, it is just like Java VM, right?
- 16. Thee Virtualization Approaches Full Virtualization Paravirtualization Hardware-assisted Virtualization
- 17. Full Virtualization – Everything is virtualized – Full hardware emulation – Emulation = latency
- 18. Privileged Instructions – Privileged instructions: OS kernel and device driver access to system hardware – Trapped and emulated by VMM
- 19. Pros and Cons – Full Virtualization • Pros – Disaster recovery, failover – Virtual appliance deployment – Legacy code on non-legacy hardware • Cons – LATENCY of core four resources – RAM performance reduced 25% to 75% – Disk I/O degraded from 5% to 20% – Network performance decreased up to 10% – CPU privileged instruction dings nearing 1% to 7%
- 20. Paravirtualization –OS or system device drivers are virtualization aware Requirements: –OS level – recompiled kernel –Device level – paravirtualized or “enlightened” device drivers
- 21. Paravirtualization • Pro: fast • Con: requires a specially modified guest OS, thus precludes the ability to run off-the-shelf and legacy OS in paravirtual environments
- 22. Hardware-assisted Virtualization – Server hardware is virtualization aware – Hypervisor and VMM load at privilege Ring -1 (firmware) – Removes CPU emulation bottleneck – Memory virtualization coming in quad core AMD and Intel CPUs
- 23. Evolution of Software solutions* • 1st Generation: Full virtualization (Binary rewriting) – Software Based – VMware and Microsoft Time • 3rd Generation: Silicon- based (Hardware- assisted) virtualization – Unmodified guest – VMware and Xen on virtualization-aware hardware platforms • 2nd Generation: Paravirtualization – Cooperative virtualization – Modified guest – VMware, Xen Dynamic Translation Virtual Machine Hardware Operating System Virtual Machine … Hypervisor Hardware VMVM Hardware Virtual Machine Virtual Machine … Virtualization Logic Hypervisor … *This slide is from Intel® Corporation
- 25. How to ensure that different distributed applications do not get into each other’s way?
Editor's Notes
- #8: Hardware and low-level systems software change quickly High-level software (middleware, applications) changes more slowly
- #13: Or sitting and waiting until the next spike in demand
- #19: http://en.wikipedia.org/wiki/Ring_%28computer_security%29 Privilege rings for the x86 available in protected mode Microsoft&apos;s Ring-1 design structure as part of their NGSCB initiative and hypervisors embedded in firmware such as Intel VT-x (formerly Vanderpool).