CloudResearch云服务09Word下载.docx
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D.Breitgand
E.Levy
A.Galis
K.Nagin
I.Llorente
R.Montero
Y.Wolfsthal
E.Elmroth
J.Caceres
M.Ben-Yehuda
W.Emmerich
F.Galan´
Abstract
Theemergingcloudcomputingparadigmisrapidlygainingmomentumasanalterna-tivetotraditionalIT.However,contemporarycloudcomputingofferingsaremostlygearedtowardsWeb2.0styleapplicationsandonlyrecentlyhavebeguntoaddresstheneedsofenterprise-gradesolutions,suchassupportforinfrastructure-levelSLAs.
Toaddressthechallengesanddeficienciesinthecurrentstateoftheart,weproposeamodular,extensiblecloudarchitecturewithintrinsicsupportforBusinessServiceMan-agement(BSM)andfederationofclouds.Ourgoalistofacilitateanopen,service-based,on-lineeconomy,whereresourcesandservicesaretransparentlyprovisionedandmanagedacrosscloudsonanon-demandbasisatcompetitivecostswithhighqualityofservice.
WepresentthevisiondrivingtheRESERVOIRproject-anarchitecturethatallowsprovidersofcloudinfrastructuretodynamicallypartnerwitheachothertocreateaseem-inglyinfinitepoolofITresourceswhilefullypreservingtheautonomyoftechnologicalandbusinessmanagementdecisions.Tothisend,RESERVOIRleveragesandextendsthead-vantagesofvirtualizationandembedsautonomousmanagementintotheinfrastructure.Atthesametime,theRESERVOIRapproachaimstoachieveaveryambitiousgoal-creatingafoundationfornext-generationenterprise-gradecloudcomputing.
1Introduction
IntheWeb2.0era,companiesgrowfrominceptiontoamassivescaleatincrediblerates.Forexample,MySpaceacquired20millionusersintwoyears;
YouTubereachedthesamenumberofusersinjust16months[1].However,toleveragethispotentialrateofgrowth,companiesmustproperlyaddresscriticalbusinessdecisionsrelatedtotheirservicedeliveryinfrastructure.
TheemergingCloudComputingparadigm[2],asexemplifiedbytheAmazonElasticCom-puteCloud(EC2),representsapromisingconceptualfoundationforhostinganddeploymentofweb-basedserviceswhiletheoreticallyrelievingserviceprovidersfromtheresponsibilityofprovisioningthecomputationalresourcesneededtosupporttheseservices.Cloudcomputingoffersmultipleadvantages:
itallowsindividualsorcompanieswithmarketdomainexpertisetobuildandruntheirSoftwareasaService(SaaS)companywithminimaleffortinsoftwaredevel-opmentandwithoutmanaginganyhardwareoperations.Thishelpsreducesoftwarecomplexityandcosts,expeditetime-to-market,andenhanceaccessibilityofconsumers.
Withcloudcomputing,companiescanleaseinfrastructureresourceson-demandfromavir-tuallyunlimitedpool.The“payasyougo”billingmodelapplieschargesfortheactuallyused
TheresearchleadingtotheseresultsispartiallysupportedbytheEuropeanCommunity’sSeventhFrameworkProgramme(FP7/2001-2013)undergrantagreementn215605.
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resourcesperunittime.Thisway,abusinesscanoptimizeitsITinvestmentandimproveavail-abilityandscalability.
Whilecloudcomputingholdshugepromiseforthefutureofservicecomputing,anumberofinherentdeficienciesincurrentofferingscanbepointedout:
Inherentlylimitedscalabilityofsingle-providerclouds:
Althoughmostinfrastructurecloudproviderstodayclaiminfinitescalability,inrealityitisreasonabletoassumethateventhelargestplayersmaystartfacingscalabilityproblemsasCloudComputingusagerateincreases.Inthelongterm,scalabilityproblemsmaybeexpectedtoaggravateascloudprovidersserveanincreasingnumberofon-lineservices,eachaccessedbymassiveamountsofglobalusersatalltimes.
Lackofinteroperabilityamongcloudproviders:
Contemporarycloudtechnologieshavenotbeendesignedwithinteroperabilityinmind.Thisresultsinaninabilitytoscalethroughbusinesspartnershipsacrosscloudsproviders.Inaddition,itpreventssmallandmediumcloudinfrastructureprovidersfromenteringthecloudprovisioningmarket.Overall,thisstiflescompetitionandlocksconsumerstoasinglevendor.
Nobuilt-inBusinessServiceManagementsupport:
BusinessServiceManagement(BSM)isamanagementstrategythatallowsbusinessestoaligntheirITmanagementwiththeirhighlevelbusinessgoals.ThekeyaspectofBSMisServiceLevelAgreement(SLA)manage-ment.CurrentcloudcomputingsolutionsarenotdesignedtosupporttheBSMpracticesthatarewellestablishedinthedailymanagementoftheenterpriseITdepartments.Asaresult,enterpriseslookingattransformingtheirIToperationstocloud-basedtechnologiesfaceanon-incrementalandpotentiallydisruptivestep.
Wearguethatnoneoftheseproblems,aswellasothermajorproblemssuchassecurityandavailability,arenotremediablebyretrofittingexistingarchitectures.Onthecontrary,theseissuesshouldbeaddressedbyproperdesignofacloudcomputingarchitecturefrombasicprinciples.Inthispaper,weproposeareferencemodelandarchitecturethatsystematicallyaddresssomeofthosedeficienciesandserveasapotentialfoundationfordeliveringITservicesasutilitiesovertheInternet.
1.1TheRESERVOIRApproach
TheRESERVOIRvisionistoenableon-demanddeliveryofITservicesatcompetitivecosts,withoutrequiringalargecapitalinvestmentininfrastructure.OurmodelisinspiredbyastrongdesiretolikenthedeliveryofITservicestothedeliveryofcommonutilities.Forexample,acommonscenariointheelectricgridisforonefacilitytodynamicallyacquireelectricityfromaneighboringfacilitytomeetaspikeindemand.Wedeemthatsimilarlytootherindustries,wherenosingleproviderservesallcustomersatalltimes,next-generationcloudcomputinginfrastruc-tureshouldsupportamodelwheremultipleindependentproviderscancooperateseamlesslytomaximizetheirbenefit.
Morespecifically,webelievethattotrulyfulfillthepromiseofcloudcomputing,thereshouldbetechnologicalcapabilitiestofederatedisparatedatacenters,includingthoseownedbyseparateorganizations.Onlythroughfederationandinteroperabilitycaninfrastructureproviderstakeadvantageoftheiraggregatedcapabilitiestoprovideaseeminglyinfiniteservicecomputingutility.Informally,werefertotheinfrastructurethatsupportsthisparadigmasafederatedcloud.
Anadditionalimportantadvantageofferedbythefederatedcloudapproachisthatitdemoc-ratizesthesupplysideofcloudcomputingandallowssmallandmedium-sizedbusinessesandnewentrantstobecomecloudproviders.Thisencouragescompetitionandinnovation.
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Asdiscussedabove,oneofthelimitingfactorsincurrentcloudcomputingofferingsisthelackofsupportforBSM,specificallyforbusiness-alignedSLAmanagement.WhilespecificcloudcomputingsolutionscanbeenhancedwithsomeaspectsofBSM,theprovisioningofcomplexservicesacrossafederatednetworkofpossiblydisparatedatacentersisadifficultandyetunsolvedproblem.Aservicemaybeacompositionofnumerousdistributedresources,includingcomputing,storage,andnetworkelements.Provisioningsuchaserviceconsumesphysicalresources,butshouldnotcauseanSLAviolationofanyotherrunningapplicationwithaprobabilitylargerthansomepredefinedthreshold.AsSLAsserveasriskmitigationmechanisms,thisthresholdrepresentstheriskthatacloudproviderandthecloudcustomerarewillingtoaccept.
WithBSM,applicationsareproperlydimensioned,andtheirnon-functionalcharacteristics(e.g.,performance,availability,security,etc.),governedbySLAs,areensuredwithoptimalcostthroughcontinuousIToptimization.Wearguethatduetotheimmensescaleenvisionedbycloudcomputing,supportforBSMshouldbemaximallyautomatedandembeddedintothecloudinfrastructure.
IntheRESERVOIRmodel,eachinfrastructureproviderisanautonomousbusinesswithitsownbusinessgoals.Aproviderfederateswithotherproviders(i.e.,otherRESERVOIRsites)basedonitsownlocalpreferences.TheITmanagementataspecificRESERVOIRsiteisfullyautonomousandgovernedbypoliciesthatarealignedwiththesite’sbusinessgoals.Toopti-mizethisalignment,onceinitiallyprovisioned,resourcescomposingaservicemaybemovedtootherRESERVOIRsitesbasedoneconomical,performance,oravailabilityconsiderations.Ourresearchaddressesthoseissuesandseekstominimizethebarrierstodeliveringservicesasutilitieswithguaranteedlevelsofserviceandproperriskmitigation.
Cloudcomputingisthelatestincarnationofageneral-purposepubliccomputingutility.Inrecentyearswehaveseenthemanyeffortstowardscomputingasautility-fromgridcomput-ing[3],whichmadesignificantprogressintheareaofhighperformancescientificcomputing,toattemptsatbuildingenterprise-levelutilities[4].However,noneoftheseattemptshavemateri-alizedintoageneralpurposecomputeutilityaccessiblebyanyone,atanytime,fromanywhere.
Whatmakescloudcomputingdifferentisthatindustrytrendssuchasubiquityofbroad-bandnetworks,fastpenetrationofvirtualizationtechnologyforx86-basedservers[5],andtheadoptionofSoftwareasaService[6]arefinallycreatinganopportunityandaneedforaglobalcomputingutility.Thereluctancetouseon-lineservicesasareplacementfortraditionalsoftwareislessening–thesuccessofcompaniessuchasprovesthatwiththerightsetofsecuritywarrantiesandacompetitiveprice,companiesarewillingtotrusteventheirmostvalu-abledata–customerrelations–toanon-lineserviceprovider.Atthesametime,virtualizationhasmadeitpossibletode