网格计算和云计算 360 度比较原文.docx

网格计算和云计算 360 度比较原文.docx

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网格计算和云计算360度比较原文

CloudComputingandGridComputing360-DegreeCompared

1,2,3IanFoster,4YongZhao,1IoanRaicu,5ShiyongLu

foster@mcs.anl.gov,yozha@,iraicu@cs.uchicago.edu,shiyong@wayne.edu

1DepartmentofComputerScience,UniversityofChicago,Chicago,IL,USA

2ComputationInstitute,UniversityofChicago,Chicago,IL,USA

3Math&ComputerScienceDivision,ArgonneNationalLaboratory,Argonne,IL,USA

4MicrosoftCorporation,Redmond,WA,USA

5DepartmentofComputerScience,WayneStateUniversity,Detroit,MI,USA

Abstract–CloudComputinghasbecomeanotherbuzzwordafterWeb

2.0.However,therearedozensofdifferentdefinitionsforCloudComputingandthereseemstobenoconsensusonwhataCloudis.Ontheotherhand,CloudComputingisnotacompletelynewconcept;ithasintricateconnectiontotherelativelynewbutthirteen-yearestablishedGridComputingparadigm,andotherrelevanttechnologiessuchasutilitycomputing,clustercomputing,anddistributedsystemsingeneral.ThispaperstrivestocompareandcontrastCloudComputingwithGridComputingfromvariousanglesandgiveinsightsintotheessentialcharacteristicsofboth.

1100-MileOverview

CloudComputingishintingatafutureinwhichwewon’tcomputeonlocalcomputers,butoncentralizedfacilitiesoperatedbythird-partycomputeandstorageutilities.Wesurewon’tmisstheshrink-wrappedsoftwaretounwrapandinstall.Needlesstosay,thisisnotanewidea.Infact,backin1961,computingpioneerJohnMcCarthypredictedthat“computationmaysomedaybeorganizedasapublicutility”—andwentontospeculatehowthismightoccur.

Inthemid1990s,thetermGridwascoinedtodescribetechnologiesthatwouldallowconsumerstoobtaincomputingpowerondemand.IanFosterandotherspositedthatbystandardizingtheprotocolsusedtorequestcomputingpower,wecouldspurthecreationofaComputingGrid,analogousinformandutilitytotheelectricpowergrid.Researcherssubsequentlydevelopedtheseideasinmanyexcitingways,producingforexamplelarge-scalefederatedsystems（TeraGrid,OpenScienceGrid,caBIG,EGEE,EarthSystemGrid）thatprovidenotjustcomputingpower,butalsodataandsoftware,ondemand.Standardsorganizations（e.g.,OGF,OASIS）definedrelevantstandards.Moreprosaically,thetermwasalsoco-optedbyindustryasamarketingtermforclusters.ButnoviablecommercialGridComputingprovidersemerged,atleastnotuntilrecently.

Sois“CloudComputing”justanewnameforGrid?

Ininformationtechnology,wheretechnologyscalesbyanorderofmagnitude,andintheprocessreinventsitself,everyfiveyears,thereisnostraightforwardanswertosuchquestions.

Yes:

thevisionisthesame—toreducethecostofcomputing,increasereliability,andincreaseflexibilitybytransformingcomputersfromsomethingthatwebuyandoperateourselvestosomethingthatisoperatedbyathirdparty.

Butno:

thingsaredifferentnowthantheywere10yearsago.Wehaveanewneedtoanalyzemassivedata,thusmotivatinggreatlyincreaseddemandforcomputing.Havingrealizedthebenefitsofmovingfrommainframestocommodityclusters,

wefindthatthoseclustersarequiteexpensivetooperate.Wehavelow-costvirtualization.And,aboveall,wehavemultiplebillionsofdollarsbeingspentbythelikesofAmazon,Google,andMicrosofttocreaterealcommerciallarge-scalesystemscontaininghundredsofthousandsofcomputers.Theprospectofneedingonlyacreditcardtogeton-demandaccessto100,000+computersintensofdatacentersdistributedthroughouttheworld—resourcesthatbeappliedtoproblemswithmassive,potentiallydistributeddata,isexciting!

Soweareoperatingatadifferentscale,andoperatingatthesenew,moremassivescalescandemandfundamentallydifferentapproachestotacklingproblems.Italsoenables—indeedisoftenonlyapplicableto—entirelynewproblems.

Nevertheless,yes:

theproblemsaremostlythesameinCloudsandGrids.Thereisacommonneedtobeabletomanagelargefacilities;todefinemethodsbywhichconsumersdiscover,request,anduseresourcesprovidedbythecentralfacilities;andtoimplementtheoftenhighlyparallelcomputationsthatexecuteonthoseresources.Detailsdiffer,butthetwocommunitiesarestrugglingwithmanyofthesameissues.

1.1DefiningCloudComputing

ThereislittleconsensusonhowtodefinetheCloud[49].WeaddyetanotherdefinitiontothealreadysaturatedlistofdefinitionsforCloudComputing:

Alarge-scaledistributedcomputingparadigmthatisdrivenbyeconomiesofscale,inwhichapoolofabstracted,virtualized,dynamically-scalable,managedcomputingpower,storage,platforms,andservicesaredeliveredondemandtoexternalcustomersovertheInternet.

Thereareafewkeypointsinthisdefinition.First,CloudComputingisaspecializeddistributedcomputingparadigm;itdiffersfromtraditionalonesinthat1）itismassivelyscalable,

2）canbeencapsulatedasanabstractentitythatdeliversdifferentlevelsofservicestocustomersoutsidetheCloud,3）it

isdrivenbyeconomiesofscale[44],and4）theservicescanbedynamicallyconfigured（viavirtualizationorotherapproaches）anddeliveredondemand.

Governments,researchinstitutes,andindustryleadersarerushingtoadoptCloudComputingtosolvetheirever-increasingcomputingandstorageproblemsarisingintheInternetAge.TherearethreemainfactorscontributingtothesurgeandinterestsinCloudComputing:

1）rapiddecreaseinhardwarecostandincreaseincomputingpowerandstoragecapacity,andtheadventofmulti-corearchitectureandmodernsupercomputersconsistingofhundredsofthousandsofcores;

2）theexponentiallygrowingdatasizeinscientificinstrumentation/simulationandInternetpublishingandarchiving;and3）thewide-spreadadoptionofServicesComputingandWeb2.0applications.

1.2Clouds,Grids,andDistributedSystems

ManydiscerningreaderswillimmediatelynoticethatourdefinitionofCloudComputingoverlapswithmanyexistingtechnologies,suchasGridComputing,UtilityComputing,ServicesComputing,anddistributedcomputingingeneral.WearguethatCloudComputingnotonlyoverlapswithGridComputing,itisindeedevolvedoutofGridComputingandreliesonGridComputingasitsbackboneandinfrastructuresupport.Theevolutionhasbeenaresultofashiftinfocusfromaninfrastructurethatdeliversstorageandcomputeresources（suchisthecaseinGrids）toonethatiseconomybasedaimingtodelivermoreabstractresourcesandservices（suchisthecaseinClouds）.AsforUtilityComputing,itisnotanewparadigmofcomputinginfrastructure;rather,itisabusinessmodelinwhichcomputingresources,suchascomputationandstorage,arepackagedasmeteredservicessimilartoaphysicalpublicutility,suchaselectricityandpublicswitchedtelephonenetwork.Utilitycomputingistypicallyimplementedusingothercomputinginfrastructure

（e.g.Grids）withadditionalaccountingandmonitoringservices.ACloudinfrastructurecanbeutilizedinternallybyacompanyorexposedtothepublicasutilitycomputing.

SeeFigure1foranoverviewoftherelationshipbetweenCloudsandotherdomainsthatitoverlapswith.Web2.0coversalmostthewholespectrumofservice-orientedapplications,whereCloudComputingliesatthelarge-scaleside.SupercomputingandClusterComputinghavebeenmorefocusedontraditionalnon-serviceapplications.GridComputingoverlapswithallthesefieldswhereitisgenerallyconsideredoflesserscalethansupercomputersandClouds.

Figure1:

GridsandCloudsOverview

GridComputingaimsto“enableresourcesharingandcoordinatedproblemsolvingindynamic,multi-institutionalvirtualorganizations”[18][20].Therearealsoafewkeyfeaturestothisdefinition:

Firstofall,Gridsprovidea

distributedcomputingparadigmorinfrastructurethatspansacrossmultiplevirtualorganizations（VO）whereeachVOcanconsistofeitherphysicallydistributedinstitutionsorlogicallyrelatedprojects/groups.Thegoalofsuchaparadigmistoenablefederatedresourcesharingindynamic,distributedenvironments.Theapproachtakenbythedefactostandardimplementation–TheGlobusToolkit[16][23],istobuildauniformcomputingenvironmentfromdiverseresourcesbydefiningstandardnetworkprotocolsandprovidingmiddlewaretomediateaccesstoawiderangeofheterogeneousresources.Globusaddressesvariousissuessuchassecurity,resourcediscovery,resourceprovisioningandmanagement,jobscheduling,monitoring,anddatamanagement.

Halfadecadeago,IanFostergaveathreepointchecklist[19]tohelpdefinewhatis,andwhatisnotaGrid:

1）coordinatesresourcesthatarenotsubjecttocentralizedcontrol,2）usesstandard,open,general-purposeprotocolsandinterfaces,and3）deliversnon-trivialqualitiesofservice.Althoughpoint3holdstrueforCloudComputing,neitherpoint1norpoint2isclearthatitisthecasefortoday’sClouds.ThevisionforCloudsandGridsaresimilar,detailsandtechnologiesusedmaydiffer,butthetwocommunitiesarestrugglingwithmanyofthesameissues.ThispaperstrivestocompareandcontrastCloudComputingwithGridComputingfromvariousanglesandgiveinsightsintotheessentialcharacteristicsofboth,withthehopetopaintalesscloudypictureofwhatCloudsare,whatkindofapplicationscanCloudsexpecttosupport,andwhatchallengesCloudsarelikelytofaceinthecomingyearsastheygainmomentumandadoption.Wehopethiswillhelpbothcommunitiesgaindeeperunderstandingofthegoals,assumptions,status,anddirections,andprovideamoredetailedviewofboth