Virtual Machines

7/18/2019 Virtual Machines

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Virtual Machines



Virtualization

• Virtualization deals with “extending or replacingan existing interface so as to mimic the behavior

of another system”

• Virtual system examples: virtual private network

virtual memory virtual machine



• !un legacy software on non"legacy hardware

• !un multiple operating systems on the samehardware

• #reate a manageable upgrade path

• Manage outages $expected and unexpected%dynamically



• !educe costs by consolidating services onto

the fewest number of physical machines

http://www.vmware.com/img/serverconsolidation.jpg



&on"virtualized 'ata #enters

• (oo many servers for too little work

• )igh costs and infrastructure needs * Maintenance

* &etworking

* +loor space

* #ooling

* ,ower

* 'isaster !ecovery



'ynamic 'ata #enter

• Virtualization helps us break the “one service perserver” model

• #onsolidate many services into a fewer number of

machines when workload is low reducing costs

• #onversely as demand for a particular serviceincreases we can shift more virtual machines to run

that service

•-e can build a data center with fewer total resourcessince resources are used as needed instead of being

dedicated to single services



VM workload multiplexing

* Multiplex VMs. workload on same physical server

• /ggregate multiple workload0 1stimate total capacity need

based on aggregated workload

• ,erformance level of each VM be preserved

2eparate VM

sizing

VM multiplexing

s3

s4

s5

We expect s3 < s1 + s2. Benefit of

multiplexing !



2o it is 6ust like 7ava VM right8



(hee Virtualization /pproaches

+ull Virtualization

,aravirtualization

)ardware"assisted Virtualization



+ull Virtualization

* 1verything is virtualized

* +ull hardware emulation

* 1mulation 9 latency



,rivileged nstructions

* ,rivileged instructions: ;2 kernel and devicedriver access to system hardware

* (rapped and emulated by VMM



,ros and #ons * +ull

Virtualization• Pros

* 'isaster recovery failover

* Virtual appliance deployment

* <egacy code on non"legacy hardware

• Cons * </(1&#= of core four resources

* !/M performance reduced 4>? to @>?

* 'isk A; degraded from >? to 4B?

* &etwork performance decreased up to 3B?

* #,C privileged instruction dings nearing 3? to @?



,aravirtualization

* ;2 or system devices are virtualization aware

Requirements:

* ;2 level * recompiled kernel

* 'evice level * paravirtualized or “enlightened”device drivers



,aravirtualization

• Pro: fast

• Con: reDuires a specially modified guest ;2 thus precludes the ability to run off"the"shelf and legacy ;2 in paravirtual environments



)ardware"assisted

Virtualization * 2erver hardware is virtualization aware

* )ypervisor and VMM load at

privilege !ing "3 $firmware%

* !emoves #,C emulation bottleneck * Memory virtualization coming in Duad

core /M' and ntel #,Cs



1volution of 2oftware solutionsE

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Feneration: +ullvirtualization $Ginary

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* 2oftware Gased

* VMware and

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(ime

• 5rd

Feneration: 2ilicon" based $)ardware"

assisted% virtualization

* Cnmodified guest

* VMware and Hen on

virtualization"aware

hardware platforms

• 4nd

Feneration:,aravirtualization

* #ooperative

virtualization

* Modified guest

* VMware Hen

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Virtual Machines

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