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1/13

Whats New in VMware vSphere 4:

Performance Enhancements

W H I T E P A P E R


2/13

2

VMware white paper

Sclbility enhncmnts 3

CPU enhncmnts 4

Mmoy enhncmnts 4

S t o g e n h n c m n t s 5

Ntoking enhncmnts 7

r s o u c M n g m n t e n h n c m n t s 8

Pfomnc Mngmnt enhncmnts 9

appliction Pfomnc 9

Ocl 9

SQL Sv 10Sap 10

excng 11

Summy 12

rfncs 12


3/13

VMware white paper

VMware vSphere 4, the industrys rst cloud operating system, includes several unique new eatures that allow IT organizations

to leverage the benets o cloud computing, with maximum eciency, uncompromised control, and exibility o choice.

The new VMware vSphere 4 provides signicant perormance enhancements that make it easier or organizations to virtualize

their most demanding and intense workloads. These perormance enhancements provide VMware vSphere 4 with better:

Efficiency: Optimizations resulting in reduced virtualization overheads and highest consolidation ratios.

Control: Enhancements leading to improved ongoing perormance monitoring and management, as well as

dynamic resource sizing or better scalability.

Choice: Improvements that provide several options o guest OS, virtualization technologies, comprehensive HCL,

integrations with 3rd-party management tools to choose rom.

This document outlines the key perormance enhancements o VMware vSphere 4, organized into ollowing categories:

ScalabilityEnhancements

CPU,Memory,Storage,Networking

ResourceManagement

PerformanceManagement

Finally, the white paper showcases the perormance improvements in various tier-1 enterprise applications as a result

o these benets.

Sclbility enhncmnts

A summary o the key new scalability improvements o vSphere 4 as compared to VMwares previous datacenter

product, VMware Inrastructure 3 (VI3), is shown in the ollowing table:

Ftu VI3 vSph 4

Vul Mcn CpU Coun 4 vCpUs 8 vCpUs

Vul Mcn Mmoy Mxmum 64 GB 255 GB

hos CpU Co Mxmum 32 cos 64 cos

hos Mmoy Mxmum 256 GB 1 tB

pod-on VMs eSX/eSX Mxmum 128 256

For details see Systems Compatibility Guide and Guest Operating System Installation Guide.

Additional changes that enhance the scalability o vSphere include:

64 Logical CPUs and 256 Virtual CPUs Per Host ESX/ESXi 4.0 provides headroom or more virtual machines per

host and the ability to achieve even higher consolidation ratios on larger machines.

64-bit VMkernel The VMkernel, a core component o the ESX/ESXi 4.0 hypervisor, is now 64-bit. This provides

greater host physical memory capacity and more seamless hardware support than earlier releases.

64-bit Service Console The Linux-based Service Console or ESX 4.0 has been upgraded to a 64-bit versionderived rom a recent release o a leading Enterprise Linux vendor.
http://www.vmware.com/resources/guides.htmlhttp://www.vmware.com/resources/guides.html


4/13

4

VMware white paper

New Virtual Hardware ESX/ESXi 4.0 introduces a new generation o virtual hardware (virtual hardware version 7)

which adds signiicant new eatures including:

Serial Attached SCSI (SAS) virtual device for Microsoft Cluster ServiceProvidessupportforrunningWindowsServer2008 in a Microsot Cluster Service coniguration.

IDE virtual device Ideal or supporting older operating systems that lack SCSI drivers.

VMXNET Generation 3SeetheNetworkingsection.

Virtual Machine Hot Plug SupportProvidessupportforaddingandremovingvirtualdevices,addingvirtualCPUs,and

adding memory to a virtual machine without having to power o the virtual machine.

Hardware version 7 is the deault or new ESX/ESXi 4.0 virtual machines. ESX/ESXi 4.0 will continue to run virtual

machines created on hosts running ESX Server versions 2.x and 3.x. Virtual machines that use virtual hardware version

7 eatures are not compatible with ESX/ESXi releases prior to version 4.0.

VMDirectPath for Virtual MachinesVMDirectPathI/OdeviceaccessenhancesCPUefficiencyinhandlingworkloads

that require constant and requent access to I/O devices by allowing virtual machines to directly access the underlying

hardware devices. Other virtualization eatures, such as VMotion, hardware independence and sharing o physicalI/Odeviceswillnotbeavailabletothevirtualmachinesusingthisfeature.VMDirectPathI/OfornetworkingI/Odevices

is ully supported with the Intel 82598 10 Gigabit Ethernet Controller and Broadcom 57710 and 57711 10 Gigabit

Ethernet Controller. It is experimentally supported or storage I/O devices with the QLogic QLA25xx 8Gb Fibre Channel,

theEmulexLPe120008GbFibreChannel,andtheLSI3442e-Rand3801e(1068chipbased)3GbSASadapters.

Increased NFS Datastore SupportESXnowsupportsupto64NFSsharesasdatastoresinacluster.

CPU enhncmnts

Resource Management and Processor Scheduling

The ESX 4.0 scheduler includes several new eatures and enhancements that help improve the throughput o all workloads,

with notable gains in I/O intensive workloads. This includes:

Relaxedco-schedulingofvCPUs,introducedinearlierversionsofESX,hasbeenfurtherfine-tunedespeciallyforSMPVMs. ESX4.0schedulerutilizesnewfiner-grainedlockingthatreducesschedulingoverheadsincaseswherefrequent

scheduling decisions are needed.

Thenewschedulerisawareofprocessorcachetopologyandtakesintoaccounttheprocessorcachearchitectureto

optimizeCPUusage.

For I/O intensive workloads, interrupt delivery and the associated processing costs make up a large component o the

virtualization overhead. The above scheduler enhancements greatly improve the eciency o interrupt delivery and

associated processing.

Mmoy enhncmnts

Hardware-assisted Memory Virtualization

Memory management in virtual machines difers rom physical machines in one key aspect: virtual memory addresstranslation. Guest virtual memory addresses must be translated rst to guest physical addresses using the guest OS's

page tables beore nally being translated to machine physical memory addresses. The latter step is perormed by ESX

by means o a set o shadow page tables or each virtual machine. Creating and maintaining the shadow page tables

addsbothCPUandmemoryoverhead.

Hardware support is available in current processors to alleviate this situation. Hardware-assisted memory management

capabilitiesfromIntelandAMDarecalledEPTandRVI,respectively.Thissupportconsistsofasecondlevelofpage

tables implemented in hardware. These page tables contain guest physical to machine memory address translations.

ESX4.0introducessupportfortheIntelXeonprocessorsthatsupportEPT.SupportforAMDRVIhasexistedsinceESX3.5.


5/13

VMware white paper

Figure 1 illustrates eciency improvements seen or a ew example workloads when using hardware-assisted

memory virtualization.

Whilethishardwaresupportobviatestheneedformaintainingshadowpagetables(andtheassociatedperformanceoverhead)

it introduces some costs o its own. Translation look-aside bufer (TLB) miss costs, in the orm o increased latency, are higher

withtwo-levelpagetablesthanwiththeone-leveltable.Usinglargememorypages,afeaturethathasbeenavailablesince

ESX 3.5, the number o TLB misses can be reduced. Since TLB miss latency is higher with this orm o hardware virtualization

assist but large pages reduce the number o TLB misses, the combination o hardware assist and large page support that

exists in vSphere yields optimal perormance.

Stog enhncmnts

A variety o architectural improvements have been made to the storage subsystem o vSphere 4. The combination o

the new paravirtualized SCSI driver, and additional ESX kernel-level storage stack optimizations dramatically improves

storage I/O perormance with these improvements, all but a very small segment o the most I/O intensive applications

become attractive targets or VMware virtualization.

VMware Paravirtualized SCSI (PVSCSI)

Emulated versions o hardware storage adapters rom BusLogic and LSILogic were the only choices available in earlier ESX

releases. The advantage o this ull virtualization is that most operating systems ship drivers or these devices. However, this

precludes the use o perormance optimizations that are possible in virtualized environments. To this end, ESX 4.0 ships

withanewvirtualstorageadapterParavirtualizedSCSI(PVSCSI).PVSCSIadaptersarehigh-performancestorageadapters

thatoergreaterthroughputandlowerCPUutilizationforvirtualmachines.Theyarebestsuitedforenvironmentsinwhichguest applications are very I/O intensive.

PVSCSIadapterextendstothestoragestackperformancegainsassociatedwithotherparavirtualdevicessuchasthenetwork

adapterVMXNETavailableinearlierversionsofESX.Aswithotherdeviceemulations,PVSCSIemulationimproveseciencyby:

Reducingthecostofvirtualinterrupts

BatchingtheprocessingofI/Orequests

BatchingI/Ocompletioninterrupts

A urther optimization, which is specic to virtual environments, reduces the number o context switches between

theguestandVirtualMachineMonitor.EciencygainsfromPVSCSIcanresultinadditional2xCPUsavingsforFibre

Channel(FC),upto30percentCPUsavingsforiSCSI.

Apache Compile

60%

50%

40%

30%

0%

10%

Eciency Improvement

20%

SQL Server Citrix XenApp

Efficiency Improvement

Figure 1 Efficiency improvements using hardware-assisted memory virtualization


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6

VMware white paper

VMware recommends that you create a primary adapter or use with a disk that will host the system sotware (boot disk)

andaseparatePVSCSIadapterforthediskthatwillstoreuserdata,suchasadatabaseormailbox.Theprimaryadapter

will be the deault or the guest operating system on the virtual machine. For example, or virtual machines with

MicrosoftWindows2008guestoperatingsystems,LSILogicisthedefaultprimaryadapter.

iSCSI Support Improvements

vSphere 4 includes signicant updates to the iSCSI stack or both sotware iSCSI (that is, in which the iSCSI initiator runs at

the ESX layer) and hardware iSCSI (that is, in which ESX leverages a hardware-optimized iSCSI HBA). These changes ofer

dramatic improvement o both perormance as well as unctionality o both sotware and hardware iSCSI and delivering

signicantreductionofCPUoverheadforsoftwareiSCSI.EciencygainsforiSCSIstackcanresultin7-26percentCPU

savings or read, 18-52 percent or write.

S/W iSCSI

1.2

1

0.8

0.6

0

0.2

LSI Logic

pvscsi

0.4

Protocol

Fibre Channel

PVSCSI Efficiency of 4K BlockI/0s

HW iSCSI

60

50

40

30

0

10

Read

Write

20

SW iSCSI

iSCSI % CPU Efficiency Gains, ESX 4 vs. ESX 3.5

Figure 2 Efficiency gains with PV SCSI adapter

Figure 3 iSCSI% CPU Efficiency Gains, ESX 4 vs. ESX 3.5


7/13

VMware white paper

Software iSCSI and NFS Support with Jumbo Frames

vSphere4addssupportforJumboFrameswithbothNFSandiSCSIstorageprotocolson1Gbaswellas10GbNICs.

The 10Gb support or iSCSI allows or 10x I/O throughput more details in networking section below.

Improved I/O Concurrency

Asynchronous I/O execution has always been a eature o ESX. However, ESX 4.0 has improved the concurrency o the

storagestackwithanI/OmodethatallowsvCPUsintheguesttoexecuteothertasksafterinitiatinganI/Orequestwhile

theVMkernelhandlestheactualphysicalI/O.InVMwaresFebruary2009announcementonOracleDBOLTPperformance

the gains attributed to this improved concurrency model were measured at 5 percent.

Ntoking enhncmnts

Signicant changes have been made to the vSphere 4 network subsystem, delivering dramatic perormance improvements.

VMXNET Generation 3

vSphere4includes,VMXNET3,thethirdgenerationofparavirtualizedNICadapterfromVMware.NewVMXNET3features

overpreviousversionofEnhancedVMXNETinclude: MSI/MSI-Xsupport(subjecttoguestoperatingsystemkernelsupport)

ReceiveSideScaling(supportedinWindows2008whenexplicitlyenabledthroughthedevice'sAdvancedconfigurationtab)

IPv6checksumandTCPSegmentationOffloading(TSO)overIPv6

VLANoff-loading

LargeTX/RXringsizes(configuredfromwithinthevirtualmachine)

Network Stack Performance and Scalability

vSphere 4 includes optimizations to the network stack that can saturate 10Gbps links or both transmit and receive side

networkI/O.TheimprovementsintheVMkernelTCP/IPstackalsoimprovebothiSCSIthroughputaswellasmaximum

network throughput or VMotion.

vSphere 4 utilizes transmit queues to provide 3X throughput improvements in transmit perormance or small packet sizes.

vSphere4supportsLargeReceiveOoad(LRO),afeaturethatcoalescesTCPpacketsfromthesameconnectionto

reduceCPUutilization.UsingLROwithESXprovides40percentimprovementinboththroughputandCPUcosts.

1 VM 4 VMs 8 VMs

100%

80%

60%

0%

20%

Gains Over ESX 3.5

40%

16 VMs

Network Transmit Throughput Improvement

Figure 4 Network Transmit Throughput Improvement for vSphere 4


8/13

8

VMware white paper

rsouc Mngmnt enhncmnts

VMotion

PerformanceenhancementsinvSphere4reducetimetoVMotionaVMbyupto75percent.

Storage VMotion Performance

Storage VMotion is now ully supported (experimental beore) and has much improved switchover time. For very I/O

intensive VMs, this improvement can be 100x. Storage VMotion leverages a new and more ecient block copy mechanism

calledChangedBlockTracking,minimizingCPUandmemoryresourceconsumptionontheESXhostuptotwotimes.

During SPECjbb (ACTIVE)

Seconds(lowerisbet

ter)

600.00

500.00

400.00

300.00

0.00

100.00

4GB ESX 3.5

4GB ESX 4

200.00

After SPECjbb (IDLE)

Elapsed VMotion Time

Storage VMotion Time

ESX 3.5 ESX 4

1200

1000

800

600

0

200

400

Figure 5 Decreased Storage VMotion Time

20 VM Provisioning Time

ESX 3.5

1200

1000

800

600

0

200

400

ESX 4

Figure 6 Improved VMFS Performance

Figure 7 Performance Enhancements Lead to a Reduced Time to VMotion


9/13

VMware white paper

VM Provisioning

VMFS perormance improvements ofer more ecient VM creation and cloning. This use case is especially important

with vSpheres more ambitious role as a Cloud operating system.

Pfomnc Mngmnt enhncmnts

Enhanced vCenter Server Scalability

As organizations adopt server vir tualization at an unprecedented level, the need to manage large scale virtual data

centers is growing signicantly. To address this, vCenter Server, included with vSphere 4, has been enhanced to manage

up to 300 hosts and 3000 virtual machines. You also have the ability to link many vCenter Servers in your environmentwith vCenter Server Linked Mode to manage up to 10,000 virtual machines rom a single console.

vCenter Performance Charts Enhancements

PerformancechartsinvCenterhavebeenenhancedtoprovideasingleviewofallperformancemetricssuchasCPU,

memory, disk, and network without navigating through multiple charts. In addition, the perormance charts also

include the ollowing improvements:

Aggregatedchartsshowhigh-levelsummariesofresourcedistributionthatisusefultoidentifythetopconsumers.

Thumbnailviewsofhosts,resourcepools,clusters,anddatastoresallowforeasynavigationtotheindividualcharts.

Drilldowncapabilityacrossmultiplelevelsintheinventoryhelpsin isolatingtherootcauseofper formance

problems quickly.

Detaileddatastorelevelviewsshowutilizationbyfiletypeandunusedcapacity.

appliction Pfomnc

Oracle

VMwaretestinghasshownthatrunningaresource-intensiveOLTPbenchmark,basedonanon-comparable

implementationoftheTPC-C*workloadspecication,OracleDBinan8-vcpuVMwithvSphere4achieved85percentof

native perormance. This workload demonstrated 8,900 database transactions per second and 60,000 disk input/outputs

persecond(IOPS).TheresultsdemonstratedinthisproofpointrepresentthemostI/O-intensiveapplication-based

workload ever run in an X86 vir tual environment to date.

*Thebenchmarkwasafair-useimplementationoftheTPC-Cbusinessmodel;theseresultsarenotTPC-Ccompliantresults,andnot

comparabletoocialTPC-Cresults.TPCBenchmarkisatrademarkoftheTPC.

25

ESX 3.5

512 VM Boot Storm (FCP)

ESX 4

20

15

0

5

10

512 VM Boot Time(Fibre Channel)

Figure 8 Time to Boot 512 VDI VMS


10/13

10

VMware white paper

The results above were run on a server with only eight physical cores, resulting in an 8-way VM conguration that was not

under-committingthehost.TheslightlylesscommittedfourvCPUcongurationranat88percentofnative.

SQL Server

RunninganOLTPbenchmarkbasedonanon-comparableimplementationoftheTPC-E*workloadspecication,aSQL

ServervirtualmachinewithfourvirtualCPUsonvSphere4.0showed90percenteciencywithrespecttonative.The

SQLServerVMwitha500GBdatabaseperformed10,500IOPSand50Mb/sofnetworkthroughput.

SAP

VMwaretestingdemonstratedthatrunningSAPinaVMwithvSphere4scaledlinearlyfromonetoeightvCPUs

perVMandachieved95percentofnativeperformanceonastandard2-tierSAPbenchmark.Thismulti-tieredapplication

architectureincludestheSAPapplicationtierandback-endSQLServerdatabaseinstantiatedinasinglevirtualmachine.

2-processor 4-processor 8-processor

3

3.5

4

4.5

2.5

2

1.5

0

0.5

ESX 4

Native

1

ESX 4 Oracle DB VM Throughout,as Compared to 2-CPU Native Configuration

*Thebenchmarkwasafair-useimplementationoftheTPC-Cbusinessmodel;theseresultsarenotTPC-Ccompliantresults,and

notcomparabletoocialTPC-Cresults.TPCBenchmarkisatrademarkoftheTPC.

Figure 9 Comparison of Oracle DB VM Throughput vs. 2-CPU Native Configuration

1 cpu 2 cpu

RelativeScalingR

atio

4 cpu

3

4

2

0

Native

VMware VM

1

ESX 4 SQL Server VM Throughput,

as Compared to 1 CPU Native Configuration

Figure 10 Comparison of vSphere 4 SQL Server VM Throughput vs. Native Configuration


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1

VMware white paper

Exchange

Microsot Exchange Server is one o the most demanding applications in todays datacenters, save the very largest databases

beingdeployed.PreviousworkonvirtualExchangedeploymentsshowedVMwaresabilitytoimproveperformance

rom native congurations by designing an Exchange architecture with a greater number o mailbox instances running

ewer mailboxes per instance.

WiththeperformanceenhancementsaddedtovSphere4singleVMExchangemailboxeshavebeendemonstrated

at up to 8,000 mailboxes per instance. This means that Exchange administrators will have the option o choosing the

higher perorming smaller mailboxes or the more cheaply licensed large mailbox servers.

1 cpu 2 cpu

RelativeScalingR

atio

4 cpu 8 cpu

6

8

4

0

Native

VMware VM

2

ESX 4 SAP VM Throughout,as Compared to1 CPU Native Configuration

1 VM 2 VMs

95percentilelate

ncy(ms)

Users(Thousands)

4 VMs 6 VMs 8 VMs

6

7

8

9

5

4

3

0

1

2

200

250

300

150

100

0

50

Users (thousands) 95 percentile latency

#VCPUs >#PCPUs

ESX 4 Exchange Mailbox Count and Latency

Figure 11 Comparison of ESX 4 SAP VM Throughput vs. Native Configuration

Figure 12 vSphere performance enhancements with Microsoft Exchange


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VMware white paper

Summy

VMware innovations continue to make VMware vSphere 4 the industry standard or computing in data centers o all sizes

and across all industries. The numerous perormance enhancements in VMware vSphere 4 enable organizations to geteven more out o their virtual inrastructure and urther reinorce the role o VMware as industry leader in virtualization.

vSphere represents dramatic advances in perormance compared to VMware Inrastructure 3 to ensure that even the

most resource intensive and scale out applications such as large databases and Microsot Exchange email systems can

run on private clouds powered by vSphere.

rfncs

Performance Evaluation of AMD RVI Hardware Assist

http://www.vmware.com/pdf/RVI_performance.pdf

Performance Evaluation of Intel EPT Hardware Assist

http://www.vmware.com/pdf/Perf_ESX_Intel-EPT-eval.pdf
http://www.vmware.com/pdf/RVI_performance.pdfhttp://www.vmware.com/pdf/Perf_ESX_Intel-EPT-eval.pdfhttp://www.vmware.com/pdf/Perf_ESX_Intel-EPT-eval.pdfhttp://www.vmware.com/pdf/RVI_performance.pdf


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VMware, Inc. 3401 Hillview Ave Palo Alto CA 94304 USA Tel 877-486-927 3 Fax 650-427-50 01 www.vmware.com

Copyright 2009 VMware, Inc. All rights reserved. This product is protected by U.S. and international copyright and intellectual

property laws. VMware products are covered by one or more patents listed at http://www.vmware.com/go/patents.

VMware is a registered trademark or trademark of VMware, Inc. in the United States and/or other jurisdictions. All other

marks and names mentioned herein may be trademarks of their respective companies. VMW_09Q1_WP_vSpherePerformance_P13_R1

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