信息基礎(chǔ)設(shè)施

InformationInfrastructure

Lecture051Withorganizations’growingneedsforacomprehensiveinformationsystemsinfrastructure,anumberofsolutionshaveemergedandarecontinuingtoemerge.Whilesomeofthesesolutionsarealreadycommonbusinesspractice,othersarejustnowstartingtobeadopted.2DesigningtheInformationSystemsInfrastructureBothbusinessesandresearchfacilitiesfaceanever-increasingneedforcomputingperformance.Forexample,automanufacturers,suchJapaneseToyota,uselargesupercomputerstosimulateautomobilecrashesaswellasevaluatedesignchangesforvibrationsandwindnoise.3ManagingtheHardwareInfrastructureWhilenoteveryorganizationfacessuchlarge-scalecomputingproblems,thedemandsforcomputingresourcesareoftenfluctuating.Thismightleadstoeitherhavingtoofewresourcesforsomeproblemsorhavingtoomanyidleresourcesmostofthetime.4Toaddressthisproblem,manyorganizationsnowturnto:on-demandcomputingforfluctuatingcomputationneedsgridcomputingforsolvinglarge-scaleproblemsautonomiccomputingforincreasingreliability.5Inalmosteveryorganization,demandforindividualISresourcesishighlyfluctuating.Forexample,somehigh-bandwidthapplications,suchasvideoconferencing,maybeneededonlyduringcertaintimesoftheday,orsomeresourceintensivedata-miningapplicationsmayonlybeusedinirregularintervals.On-demandcomputingisawaytoaddresssuchfluctuatingcomputingneeds;here,theavailableresourcesareallocatedonthebasisofusers’needs(usuallyonapay-per-usebasis).6On-DemandComputingForexample,morebandwidthwillbeallocatedtoavideoconference,whileotheruserswhodonotneedthebandwidthatthattimereceiveless.Similarly,auserrunningcomplexdataminingAlgorithmswouldreceivemoreprocessingpowerthanausermerelydoingsomewordprocessing.7Attimes,organizationspreferto“rent”resourcesfromanexternalprovider.Thisformofon-demandcomputingisreferredtoasutilitycomputing,wheretheresourcesintermsofprocessing,datastorage,ornetworkingarerentedonanas-neededbasis.Organizationreceivesabillfortheservicesusedfromtheproviderattheendofeachmonth8Formanycompanies,utilitycomputingisaneffectivewayformanagingfluctuatingdemandaswellascontrollingcosts;inessence,alltasksassociatedwithmanaging,maintaining,andupgradingtheinfrastructurearelefttotheexternalproviderandaretypicallybundledintothe“utility”bill—ifyoudon’tuse,youdon’tpay.Also,aswithyourutilitybill,customersarechargednotonlyonoverallusagebutalsoonpeakusage(i.e.,differentratesfordifferenttimesoftheday).10GridComputingAlthoughtoday’ssupercomputershavetremendouscomputingpower,sometasksareevenbeyondthecapacityofasupercomputer.Indeed,somecomplexsimulationscantakeayearorlongertocalculateevenonasupercomputer.Sometimes,anorganizationoraresearchfacilitywouldhavetheneedforasupercomputerbutmaynotbeabletoaffordonebecauseoftheextremelyhighcost.11Forexample,thefastestsupercomputerscancostmorethan$200million,andthisdoesnotrepresentthe“totalcostofownership,”whichalsoincludesalltheotherrelatedcostsformakingthesystemoperational(e.g.,personnel,facilities,storage,software,andsoon)Additionally,theorganizationmaynotbeabletojustifythecostbecausethesupercomputermaybeneededonlyoccasionallytosolveafewcomplexproblems.Inthesesituations,organizationshavehadtoeitherrenttimeonasupercomputerordecidedsimplynottosolvetheproblem.12However,arelativelyrecentinfrastructuretrendforovercomingcostoruselimitationsistoutilizegridcomputing.Gridcomputingreferstocombiningthecomputingpowerofalargenumberofsmaller,independent,networkedcomputers(oftenregulardesktopPCs)intoasolidsysteminordertosolveproblemsthatonlysupercomputerswerepreviouslycapableofsolving.1314Whilesupercomputersareveryspecialized,gridcomputingallowsorganizationstosolvebothverylarge-scaleproblemsaswellasmultiple(concurrent)smallerproblems.Tomakegridcomputingwork,largecomputingtasksarebrokenintosmallchunks,eachofwhichcanthenbecompletedbytheindividualcomputers15However,astheindividualcomputersarealsoinregularuse,theindividualcalculationsareperformedduringthecomputers’idletimesoastomaximizetheuseofexistingresources.Forexample,whenwritingareport,weusedonlyminimalresourcesonourcomputers(i.e.,wetypicallyusedonlyawordprocessor,theInternet,maybee-mail);ifourcomputerswerepartofagrid,theunusedresourcescouldbeutilizedtosolvelarge-scalecomputingproblems.16Thisisespeciallyusefulforcompaniesoperatingonaglobalscale.Ineachcountry,manyoftheresourcesareidleduringthenighthours,oftenmorethan12hoursperday.Becauseoftimezonedifferences,gridcomputinghelpsutilizethoseresourcesconstructively.OnewaytoputtheseresourcesintousewouldbetojointheBerkeleyOpenInfrastructureforNetworkComputing(BOINC),whichletsindividuals“donate”computingtimeforvariousresearchprojects,suchassearchingforextraterrestrialintelligence(SETI@home)orrunningclimatechangesimulations.17However,asyoucanimagine,gridcomputingposesanumberofdemandsintermsoftheunderlyingnetworkinfrastructureorthesoftwaremanagingthedistributionofthetasks.Further,manygridsperformonthespeedoftheslowestcomputer,thusslowingdowntheentiregrid.Manycompaniesstartingoutwithagridcomputinginfrastructureattempttoovercometheseproblemsbyusingadedicatedgrid.18Inadedicatedgrid,theindividualcomputers,ornodes,arejusttheretoperformthegrid’scomputingtasks;inotherwords,thegridconsistsofanumberofhomogeneouscomputersanddoesnotuseunutilizedresources.Adedicatedgridiseasiertosetupandmanageandisformanycompaniesmuchmorecosteffectivethanpurchasingasupercomputer.Asthegridevolvesandnewnodesareadded,dedicatedgridsbecomemoreheterogeneousovertime.19AnotherrecenttrendinIShardwareinfrastructuremanagementisedgecomputing.Withthedecreaseincostforprocessinganddatastorage,computing

tasksarenowoftensolvedattheedgeofacompany’snetwork.Inotherwords,ratherthanhavingmassive,centralizedcomputersanddatabases,multiplesmallerserversarelocatedclosertotheindividualusers.20EdgeComputingThisway,resourcesintermsofnetworkbandwidthandaccesstimearesaved.Ifacomputerneedsseveralhourstocomputeacertainproblem,itmightbeagoodchoicetosendthetaskoveranetworktoamorepowerfulcomputerthatmightbeabletosolvethatproblemfaster.However,asthecostsforcomputingpowerhavedecreasedtremendouslyoverthepastyears,manyproblemscannowbecomputedlocallywithinamatterofseconds,soitisnotcost-effectivetosendsuchproblemsoveranetworktoaremotecomputer21Tosaveresources,manybusinessesuseedgecomputingfortheironlinecommercesites.Insuchcases,customersinteractwiththeserversofanedge-computingserviceprovider(suchasAkamai).Theseservers,inturn,communicatewiththebusiness’computers.Thisformofedgecomputinghelpstoreducewaittimesfortheconsumers,asthee-commercesitesarereplicatedonAkamai’sservers,whileatthesametimereducingthenumberofrequeststothecompany’sowninfrastructure.22Thisprocessnotonlysavesvaluableresourcessuchasbandwidthbutalsoofferssuperiorperformancethatwouldotherwisebetooexpensivefororganizationstooffer.Akamai’sservicesareutilizedbyorganizationssuchasNBC,FoxSports,BMW,andVictoria’sSecret.23OnemajordrawbackofthesehardwareinfrastructuretrendsandthedemandsforISinfrastructureingeneralistheincreasedcomplexityofsuchsystems.Whereastheprimaryreasonforhavingthisinfrastructureistheutilizationoftheresources,thetimeandmoneyneededtomanagetheseresourcesdon’taddvaluetotheorganization;infact,somepeoplebelievethatthecostsofmanagingthesesystemsunderminethebenefitsthesesystemsprovide,eveniftheorganizationdecidestouseoutsideservices.24AutonomicComputingToovercomethis,academicandindustryresearchers(e.g.atIBM)havebegunworkingonautonomiccomputingsystems,whichareself-managing,meaningtheyneedonlyminimalhumaninterventiontooperate.Inotherwords,inatraditionalcomputingenvironment,systemoperatorsoftenhavetofine-tunethecomputer’sconfigurationinordertomostefficientlysolveaparticulartypeofcomplexproblem.25Inanautonomiccomputingenvironment,theultimategoalistoallowthesystemtodoeverythingelseonitsown,completelytransparenttotheuser.Inordertoachievethis,anautonomiccomputingsystemmustknowitselfandbeself-configuring,selfoptimizing,self-healing,andself-protecting.2627Inordertooptimallyperformdifferenttasks,anautonomicsystemmustknowitself;thatis,itmustknowitsconfiguration,capacity,andcurrentstatus,butitmustalsoknowwhichresourcesitcandrawon.Second,inordertobeabletousedifferentresourcesbasedondifferentneeds,thesystemshouldbeself-configuringsothattheuserdoesnothavetotakecareofanyconfigurationissues.28Further,asanypartsofasystemcanmalfunction,anautonomicsystemshouldbeself-healingsothatanypotentialproblemsaredetectedandthesystemisreconfiguredsoastoallowtheusertocontinueperformingthetasks,evenifpartsofthesystemarenotoperational.Finally,asalmostanycomputersystemcanbethetargetforanattack,autonomiccomputingsystemsmustbeawareofanypotentialdangersandmustbeabletoprotectthemselvesfromanymaliciousattacks(e.g.,byautomaticallyquarantininginfectedpartsofasystem).29CloudComputingisageneraltermusedtodescribeanewclassofnetworkbasedcomputingthattakesplaceovertheInternet,basicallyasteponfromUtilityComputingacollection/groupofintegratedandnetworkedhardware,softwareandInternetinfrastructure(calledaplatform).UsingtheInternetforcommunicationandtransportprovideshardware,softwareandnetworking