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What Is New in VMware vSphere™ 4:Storage

W H I T E P A P E R

VMW_09Q1_WP_vSphereStorage_P10_R1.indd 1 4/16/09 4:



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VMware white paper

wht Is N in VM vSph™ 4: Stog 3Incsd Stog efficincy 3

Vul Dsk tn povsonng 3

imovd SCSi Sof ino effcncy 4

Impovd Stog rsoucs Contol 5

N vCn Sog Cbls 5

Dynmc exnson of VMFS Volums 6

Mo Stog rsoucs Choics 7

enncd Sog Vmoon 7

pluggbl Sog accu (pSa) 8vSog apis fo D pocon 8

pvulzd SCSi 9

VMDcp i/O fo Sog 9

Conclusion 9




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VMware white paper

wht Is N in VM vSph™ 4: Stog

With the launch o vSphere 4, VMware introduces a new version o the hypervisor, ESX™ 4.0 and the managementinterace, vCenter. Some key benets oered by this release are greater resource eciency, management control and

reedom o choice or virtual datacenter storage resources and connectivity options. VMware has added many new

storage management capabilities that increase disk utilization rate, provide greater control o these storage resources

and enable increased options or datastore protocol support and ormat o virtual disk ormat. These storage eaturesprovide new levels o fexibility and improved management agility or virtualization environments that run vSphere.

This document provides inormation about the ollowing storage enhancements in vSphere sorted under the ollowingcategories:

Efficiency

• VirtualDiskThinProvisioning

• ImprovediSCSISoftwareInitiatorEfficiency

Control

• NewvCenterStorageCapabilities

• DynamicExpansionofVMFSVolumes

Choice

• EnhancedStorageVMotion

• PluggableStorageArchitecture

• PVSCSIandDirectPathI/O

Incsd Stog efficincy

OnebigchallengefacingmanyITmanagersistoincreasethelevelofresourceutilizationneededtorunthedatacenter.

Specically, the amount o wasted storage resources can be greatly reduced with the use o thin provisioning, wherein

storage waste measures the amount o allocated storage that is not used. This ratio is also reerred to as the storage disk

utilizationrate.Inmostdatacentersthisnumberisoftenwellbelow50percentutilization.Toaddressthisissue,manystoragevendorshavereleasedsupportforthinprovisioningintheirstoragearrays.Anothermeanstoincreasestorage

eciencyistoreducetheCPUoverheadittakestodriveanI/Obetweenaserverandthestorage.Reductionsinthis

overhead can greatly increase the throughput o a given system.

Virtual Disk Thin Provisioning

VMware vSphere introduces ull support or the option to create thin provisioned virtual disks when deploying ormigrating Virtual Machines. vCenter has also been updated with new management screens and capabilities such as

raising alerts, alarms and improved datastore utilization reports, to enable management o over provisioned datastores.

Virtual disk thin provisioning increases the eciency o storage utilization or virtualization environments by using only

theamountofunderlyingstorageresourcesneededforthatvirtualdisk.Uponinitialallocationofthevirtualdisk,the

storagerequirementswillbegiven1MBofspaceinthedatastore.Asthatspaceislled,additional1MBchunksof

storage will be allocated or the virtual disk so that the underlying storage demand will grow as its size increases.

This capability is best understood when compared to a common practice in the airline industry: overbooking o fights.Airlinesfoundthatmanypeoplewhomadereservationsdidnotshowupfortheirights.Thereforetheairlinesbegantobookmorepassengersthantheyhadseatsavailableontheight.Inthestorageindustry,arequestfordiskslarger

than what is needed or the application creates a similar problem. Thin provisioning o storage allows an administrator

to over allocate the amount o storage resources currently available. Similar to how airlines careully optimize the use o

seats on their fights, storage administrators can also increase the utilization rates, and reduce the cost o their storageresources by over allocating them and adding more when the demand usage grows to meet the allocation.




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VMware white paper

vCenter now ully supports virtual disk thin provisioning within the virtual environment— such that a thin virtual disk is

assignedonlytheamountofspaceinthedatastoreneededforthatvirtualdisk.Inthepast,thinprovisioninghasbeenthe

defaultformatforvirtualdiskscreatedonNFSdatastoresinVirtualInfrastructure3,andhasbeenavailablethroughthecommand line or block-based datastores. However. VMware has integrated management o virtual disk thin provisioning

and now ully supports this ormat or all virtual disks with the release o vSphere.

Itisimportanttonotethatvirtualdiskthinprovisioningshouldnotbeconfusedasthesamethinprovisioningthatan

arrayvendormightoer.Infact,withvSphereyounowhavethecapabilityofdoingthinprovisioningatthedatastore

level in addition to thin provisioning at the storage array. (See Figure1 or more details)

Inadditiontousingthinprovisioningtosavespacefornewdiskallocations,manyexistingvirtualizationenvironmentscan benet rom the use o Storage VMotion™ as a means to reduce wasted (allocated yet unused) storage space. By

changing virtual disk ormats rom thick to thin in conjunction with a migration o the VM home rom one datastore to

another while the VM is up and running, some customers have ound they are able to regain upwards o 40 percent o

their storage space.

Improved iSCSI Software Initiator Efficiency

WithvSphere,VMwarehasreleasedanewiSCSIsoftwareinitiatorthatisfarmoreecientinitsuseoftheESXCPU

cyclestodrivestorageI/O.TheentireiSCSIsoftwareinitiatorstackwasrewrittenandtunedtooptimizecacheanity,

enhancetheVMkernelTCP/IPstack,andmakebetteruseofinternallocks.ThenewvSphereiSCSISWinitiatorhas

beenoptimizedforvirtualizationI/OandprovidessignicantimprovementsinCPUeciencyandthroughputwhen

comparedtotheearlier3.5version.

ThecongurationstepsforaniSCSIdatastorehavealsobeenimprovedtomakeiteasiertoprovisioniSCSIstorageforvSphere.ThenewiSCSIstacknolongerrequiresaServiceConsoleconnectiontocommunicatewithaniSCSItarget.The

securityprotectionhasalsobeenexpandedwithsupportforbi-directionalCHAPauthentication.Thisaddsanotherlevel

o security by allowing the initiator to authenticate the target. Global conguration settings made in the general tab

will also propagate down to all targets. However, these can be overridden by settings on a per target basis, so users cancongure unique parameters or each array discovered by the initiator.

Figure 1. Virtual disk thin provisioning at the datastore level

VMFS Volume/Datastore

Provisioned for ESX

Virtual Disk Provisioned for VMAs a Thin Virtual Disk

40 GB Used

15 GB Used




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VMware white paper

Impovd Stog rsoucs Contol

Asthescopeofstorageresourceshaveincreasedsignicantlywithlargedeploymentsofvirtualizationenvironments,sohastheneedforgreaterautomationandcontroloftheseresources.InthevSphererelease,vCenterhasbeenenhanced

with several new storage specic capabilities to help the virtual administrator manage these environments with a

higher degree o control. These enhancements provide administrators with proactive alerts and alarms to address issues

beore they interrupt the availability o applications running on those resources. vCenter allows setting permissions andquota limits on datastores, as well as per VM.

New vCenter Storage Capabilities

To help manage storage space in vSphere, each VM and ESX in the inventory now has its own storage tab that shows

inormation about storage resources or those objects. The vCenter inventory also has a new view or listing datastore

details. The datastore is now managed as an object within vCenter in a manner that allows the vSphere administratorto view, group, and set permissions or each datastore. vSphere also provides a detailed view o all the components in

the storage layout (See Figure2). These topology maps provide key inormation to administrators about which paths are

available, as well as the grouping o objects sharing storage resources.

Inthehighestlevelofvisibility,userscanarrangethelistofdatastoreshigher-archaically;groupingdatastoresbydepartment

(as shown in Figure2),orbyclassofservices.DetailsforeachdatastorecanbeinvestigatedtorevealwhichESXservers

areaccessingitandwhatlevelofutilizationisbeingachieved.Anewtopologymapisavailableforthesedatastoresaswell.

Figure 2. View of all components in the storage layout

Figure 3. vSphere provides increased visibility and control of storage resources




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VMware white paper

AseachVMandESXnowhasitsownstoragetab,ausercanmorequicklydeterminewhatstorageresourcesareassociated

withthoseobjects.NewstorageperformancechartsalsogiveuserstheabilitytosetalertsandalarmsforaVM,ESX,

or datastore level.

Newalertsandalarmsareakeycapabilityfortoeectivelymanagingdatastoresinwhichthinprovisioneddisksmightcreate an over allocation o storage resources. The vSphere administrator can be alerted when thin provisioned disk

growth creates a need to either increase the size o a datastore or create more ree space in that datastore beore the

lack o space causes a problem. These alerts and alarms have a set o deault values that can be customized to increase

theawarenessofactionsneedingtobetaken.Forexampleanadministratorcansetanemailalerttobesentonceadatastore lls to a certain percentage.

To augment the introduction o thin provisioning, there are a ew additional capabilities that might best be groupedundertheheadingofdynamicstoragegrowth.Oneistheabilitytogrowthesizeofthedatastoreiftheoverallocationof

virtual disks or the need or new virtual disks is required. The other is the ability to ree up space in a datastore without

having to shut down any virtual machines, in the event the datastore size cannot grow. Storage VMotion is the solution

thataddressesthelaterofthesetwo,andVMFSVolumeGrow,anewfeatureintroducedinvSphere,includesanoption

to address the rst.

Dynamic Expansion of VMFS Volumes

VMFSVolumeGrowoersanewwaytoincreasethesizeofadatastorethatresidesonaVMFSvolume.Itcomplements

thedynamicLUNexpansioncapabilitythatexistsinmanystoragearrayoeringstoday.IfaLUNisincreasedinsize,then

VMFSVolumeGrowenablestheVMFSvolumeextenttodynamicallyincreaseinsizeaswell.

PriortovSphere,theonlyoptionforincreasingthesizeofanexistingVMFSvolumewastoaddanewLUNviaaprocess

calledspanning.EveniftheLUNuponwhichtheVMFSvolumeextentresidedweretoincrease,theonlyoptionwastocreate a separate disk partition through the command line on that additional space made available and then add the

newpartitionasyoumightaddasecondLUNtotheVMFSVolume.

WithVMFSVolumeGrow,theprocessofincreasingthesizeoftheVMFSvolumeisintegratedthroughthevCenterGUI

asachoicewithintheVMFSvolumepropertiesscreen.Providedthatadditionalcapacityontheexistingextentisthere,

orhasbeenrecentlybeenincreasedincapacity,theVMFSvolumecannowbeexpandeddynamicallyuptothe2TB

limitperLUN.ForVMFSvolumesthatmightalreadyspanmultipleextents,theVMFSvolumeGrowcanbeusedtogroweach o those extents up to 2 TB as well.

Figure 4. VMFS Volume Grow enables the VMFS volume to dynamically increase in size along with the datastore

VMFS Volume/ Datastore

After Volume Grow

VMFS Volume/ Datastore

Before

300 GB 500 GB




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VMware white paper

Mo Stog rsoucs Choics

Asvirtualizationisdeployedacrossanincreasingsetofapplicationsinmanydatacenters,thereisanincreasingneedtoenable multiple storage protocols, storage rom many vendors, and many dierent types o hardware adaptors. Several

new eatures released in vSphere 4 provide additional options and choices to exist in these deployments. The ollowing

eatures enable increased options or choice in vSphere environments:

Enhanced Storage Vmotion

vSphereintroducesseveralnewcapabilitiestoStorageVMotion.WhenStorageVMotionwasintroducedinVI3release3.5,it had a ew limitations which vSphere 4 addresses. Storage VMotion is now ully integrated into vCenter and oers ull

support or migration across datastores o several protocol choices. Hence the enhanced Storage VMotion capabilities

fallsquarelyintherealmofhowvSphereprovidesanincreasedsetofchoices.FirsttheabilitytomoveaVMhomefrom

onedatastoretoanotherwhilechangingthestorageprotocolintheprocess.ThesourcedatastoremightbeFC,iSCSI,orNFS,andthetargetdatastoreanyofthosethree.Userscanalsochangefromathicktothinvirtualdiskformatorvice

versa when a VM home is migrated with Storage VMotion.

TheenhancementstoStorageVMotionalsoincludeamoreecientmigrationprocess,aswellastheremovalofthe3.5

requirementforhaving2timestheCPUandmemoryneededfortheVMthatisbeingmigrated.StorageVMotionin

vSphere leverages a change block tracking method that moves the VM home over to the new datastore in a ew iterations

insteadofusingthevirtualdisksnapshotmethodusedinthe3.5release.

Storage VMotion in vSphere provides more choices to support migrations rom one storage vendor to another, choice

o protocol, and choice o virtual disk ormat—all without having to take down the VM to relocate where it resides onthe disk.

UsingStorageVMotiontomigrateVMfromonedatastoretoanotherwhilealsoleveragingthinprovisioningprovidesameanstoreclaimwhatmightbebestdescribedaswastedstoragespace.ManyguestOSvirtualdisksareoftenallocatedfor

more storage than they truly need or their current storage requirements. However, moving those disks rom one datastore

to another while also changing the virtual disk ormat rom thick to thin in the same migration process enables that

allocatedbutunusedstoragespacetobereclaimed(asmentionedintheThinDiskVirtualProvisioningsectiononpage3 o this white paper). Figure5 shows how vCenter has the agility to leverage Storage VMotion with a change in the disk

ormat in the process o moving the VM home. This is a key enabler o eciency, control, and choice that comes romcombining two new vSphere eatures.

Figure 5. vCenter leverages Storage VMotion to change disk format in the process of moving the VM home




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VMware white paper

Pluggable Storage Architecture (PSA)

InvSphere,leveragingthirdpartystoragevendormulti-pathsoftwarecapabilitieshasbeenintroducedthroughamodular

storage architecture that allows storage partners to write a plug-in or their specic capabilities. These modules cancommunicate with the intelligence running in the storage array to determine the best path selection, as well as leveraging

parallelpathstoincreaseperformanceandreliabilityoftheI/OfromtheESXtothestoragearray.Bydefault,thenative

multipathdriver(NMP)suppliedbyVMwarewillbeused.Itcanbeconguredtosupportround-robinmultipathaswell.

However, i storage vendor module is available, it can be congured to manage the connections between the ESX andthe storage.

ThebasicversionofthosepluggablestoragemodulescanprovidePathSelectionPlug-in(PSP)optimalpathselectionforhighavailabilityandreliability.ThemoreadvancedoptionforstoragepartnerstointegratewithPSAisforthem

towriteamodulethatisStorageArrayTypePlug-in(SATP)thatcanaggregateI/Oacrossmorethanonechannelfor

optimalI/Oloadbalancingaswellashighavailability.ThispluggablestoragearchitectureisenabledbythevStorage

APIformulti-Pathing.ItisoneofseveralvStorageAPIsthathasbeenpublishedtoenablestoragepartnerstointegratetheir vendor-specic capabilities to provide more optimal perormance and to give joint customers more choice in how

theycongurethestorageresourcesforvirtualization.AnothervStorageAPIalsoreleasedinvSphereisthevStorageAPIforDataProtection.

vStorage APIs for Data Protection

ThisAPItakesthebenetsofConsolidatedBackupandmakesthemsignicantlyeasiertodeploy,whileaddingseveralnew eatures that deliver ecient, scalable backup, and restore o virtual machines.

LikeConsolidatedBackup,thisAPImakeitpossibletoooadbackupprocessingfromESXservers,ensuringthatyoudeliverthebestconsolidationratioswithoutdisruptingapplicationsandusers.ThevStorageAPIforDataProtectionenables

backup tools to directly connect the ESX servers and the virtual machines running on them without any additional

sotware installation. They add the ability to enable backup tools to do ecient incremental, dierential, and ull-image

backup and restore o virtual machines.

Figure 6. This pluggable storage architecture is enabled by the vStorage API for multi-Pathing

Pluggable Storage Architecture (PSA)

Third-Party

MPP

VMware NMP

VMware SATP VMware PSP

Third-Party SATP Third-Party SATP




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VMware white paper

Paravirtualized SCSI

VMwareParavirtualizedSCSI(PVSCSI)isaspecialpurposedriverforhigh-performancestorageadaptersthatoer

greaterthroughputandlowerCPUutilizationforvirtualmachines.TheyarebestsuitedforenvironmentsinwhichguestapplicationsareveryI/Ointensive.VMwarerequiresthatyoucreateaprimaryadapterforusewithadiskthatwillhost

thesystemsoftware(bootdisk)andaseparatePVSCSIadapterforthediskthatwillstoreuserdata,suchasadatabase.

Theprimaryadapterwillbethedefaultfortheguestoperatingsystemonthevirtualmachine.Forexample,avirtualmachinewithMicrosoftWindows2008guestoperatingsystems,LSILogicisthedefaultprimaryadapter.ThePVSCSI

driver is similar to vmxnet in that it is an enhanced and optimized special purpose driver or VM trac and works with

onlycertainGuestOSverisionthatcurrentlyincludeWindowsServer2003,2008andRHEl5.Itcanalsobesharedby

multipleVMsrunningonasingleESX,unliketheVMDirectPathI/OwhichwilldedicateasingleadaptortoasingleVM.

VMDirectPath I/O for Storage

VMDirectPathI/OdeviceaccessenhancesCPUeciencyinhandlingworkloadsthatrequireconstantandfrequent

accesstoI/Odevices.Itenablesvirtualmachinestodirectlyaccessunderlyinghardwaredevices.Thiswillmapasingle

HBAtoasingleVMandnotallowsharingoftheHBAbymorethanasingleVirtualMachine.However,othervirtualization

features,suchasVMotion,hardwareindependenceandsharingofphysicalI/OdeviceswillnotbeavailabletothevirtualmachinesusingVMDirectPathI/O.

VMDirectPathI/OisexperimentallysupportedforthefollowingstorageI/Odevices:

• QLogicQLA25xx8GbFibreChanneladapters

• EmulexLPe120008GbFibreChanneladapters

• LSI3442e-Rand3801e(1068chipbased)3GbSASadapters

Conclusion

vSphere enables many new eatures or the management o virtualization storage resources. These capabilities provide

vSphereadministratorswithnewwaystoincreaseeciencyfordiskutilizationandCPUcycles.Withautomatedproactivealerts and alarms, vCenter provides more visibility and control o storage resource allocations, deployment, and monitoring.

Also,newlevelsofreporting,topologymaps,anddatastorestatusanddetailsscreensprovideaneasywaytomanage

access and limit storage sprawl in VMware deployments. Storage VMotion has been enhanced to enable more choicesformigratingVMhomesfromonetypeofstoragetoanother.Andnally,newchoicesexistforoptimizingI/OtracforI/OintensiveVirtualMachines.

Inshort,VMwareisnowprovidingmorestorageoptionsandfeaturesthatprovidegreatercontrol,choice,andeciencyto be leveraged in a vSphere environment. vSphere 4 enables administrators to do more with less—extending the

benets provided by virtualization to reach new levels o storage eciency, management control, and additional

choices in storage connectivity.




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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 respec tive companies. VMW_09Q1_WP_vSphereStorage_P10_R1

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