data storage

Storagemedia

Disksandtapesarecommonstoragemedia.Thedatastorageorganizationdiffersdependingonthestoragemedium.Dataonthetapeisonlyaccessedinsequentialfilemode;onthedisk,sequentialaccessordirectaccesscanbeusedaccordingtotherequirementsofuse.Thedatastoragemethodiscloselyrelatedtothedatafileorganization.Thekeyistoestablishthecorrespondingrelationshipbetweenthelogicalandphysicalsequenceoftherecordsanddeterminethestorageaddresstoimprovethedataaccessspeed.

Threetypesofstoragemethods

DAS

DAS(DirectAttachedStorage)isthesameasourordinaryPCstoragearchitecture.TheexternalstoragedevicesareItisdirectlyconnectedtotheinternalbusoftheserver,andthedatastoragedeviceisapartoftheentireserverstructure.

TheDASstoragemethodismainlysuitableforthefollowingenvironments:

1)Smallnetwork

Becausethenetworkissmallinsize,theamountofdatastorageissmall,anditisnotverycomplicated.Theuseofthisstoragemethodwillnothaveagreatimpactontheserver.Andthisstoragemethodisalsoveryeconomical,suitableforenterpriseuserswithsmallnetworks.

2)Geographicallydispersednetwork

Althoughtheoverallscaleoftheenterprisenetworkisrelativelylarge,itisveryscatteredintermsofgeographicdistribution.ItisverydifficulttointerconnectbetweenthemthroughSANorNAS.Atthistime,theserversofeachbranchcanalsouseDASstorage,whichcanreducecosts.

3)Specialapplicationserver

Onsomespecialapplicationservers,suchasMicrosoft'sclusterserverortheoriginalpartitionusedbysomedatabases,storagedevicesarerequiredtobedirectlyconnectedtotheapplicationserver.

4)ImprovingDASstorageperformance

Inthevariousconnectionmethodsbetweenserversandstorage,DASwasonceconsideredtobeaninefficientstructure,anditwasinconvenientfordataprotection.Directlyconnectedstoragecannotbeshared.Therefore,itisoftenthecasethatacertainserverhasinsufficientstoragespace,whileotherservershavealargeamountofstoragespacethatisidlebutunavailable.Ifstoragecannotbeshared,thereisnobalancebetweencapacityallocationandusagerequirements.

ThedataprotectionprocessundertheDASstructureisrelativelycomplicated.Ifnetworkbackupisperformed,eachservermustbebackedupseparately,andalldatastreamsmustbetransmittedthroughthenetwork.Ifyoudonotdonetworkbackup,theneachservermustbeequippedwithasetofbackupsoftwareandtapeequipment,sothecomplexityofthebackupprocesswillgreatlyincrease.

Ifyouwanttohavehigh-availabilityDASstorage,youmustfirstreducethecostofthesolution,suchasLSI’s12Gb/sSAS,whereithasDASdirect-attachedstorage,andDAScandoagoodjobLargedatacentersprovidesupport.Forlarge-scaledatacenters,cloudcomputing,storage,andbigdata,allofthisputsforwardhigherrequirementsforDASstorageperformance.Theexplosivegrowthofcloudandenterprisedatacenterdatahasalsopromotedthemarketforhigher-speeddataaccess.Thedemandforhigh-performancestorageinterfaces,thereforeLSI12Gb/sSAScanjustmeettherequirementsofthisperformancegrowth,itcanprovidehigherIOPSandhigherthroughput,12Gb/sSASimproveshigherwritecapacityPerformance,andimprovetheoveralloverallperformanceofRAID.

Comparedwiththedirect-attachedstoragearchitecture,sharedstoragearchitecturessuchasSAN(storage-areanetwork)orNAS(network-attachedstorage)canbettersolvetheaboveproblems.Asaresult,weseethattheprocessofDASbeingeliminatedisgettingfasterandfaster.However,asof2012,DASisstillacommonmodeforconnectingserversandstorage.Infact,notonlyhasDASnotbeeneliminated,thereseemstobeatrendofresurgenceinrecentyears.

NAS

NAS(NetworkAttachedStorage)datastoragemethodhascomprehensivelyimprovedthepreviouslyinefficientDASstoragemethod.Itusesafileserverthatisindependentoftheserverandisdevelopedfornetworkdatastoragetoconnectthestoragedevicestoformanetworkbyitself.Inthisway,datastorageisnolongeraffiliatedwiththeserver,butexistsinthenetworkasanindependentnetworknodeandcanbesharedbyallnetworkusers.

AdvantagesofNAS:

1)Trueplug-and-play

NASisanindependentstoragenodethatexistsinthenetworkandinteractswiththeuser’soperatingsystem.Platformindependent,trueplugandplay.

2)Storagedeploymentissimple

NASdoesnotrelyonageneraloperatingsystem,butadoptsasimplifiedoperatingsystemdesignedforusers,specificallyfordatastorage,withbuilt-innetworkTheprotocolrequiredfortheconnectionmakesthemanagementandsettingoftheentiresystemrelativelysimple.

3)Storagedevicelocationisveryflexible

4)Managementiseasyandlowcost

NASdatastoragemethodisdesignedbasedontheexistingenterpriseEthernet,CommunicateinaccordancewiththeTCP/IPprotocol,andusefileI/Ofordatatransmission.

DisadvantagesofNAS:

(1)Lowstorageperformance(2)Lowreliability

SAN

In1991,IBMhasintroducedESCON(EnterpriseSystemConnection)technologyintheS/390server.Itisaconnectionmethodforserverswithamaximumtransmissionrateof17MB/stoaccessstoragebasedonopticalfibermedia.Onthisbasis,amorepowerfulESCONDirector(FCSWitch)wasfurtherintroduced,andasetofthemostprimitiveSANsystemwasconstructed.

SAN(StorageAreaNetwork)storagemethodcreatesanetworkofstorage.Storagenetworkingconformstothetrendofnetworkedcomputerserverarchitecture.ThesupportingtechnologyofSANisFCFiberChannel(FCFiberChannel)technology.ItisastandardintegrationestablishedbyANSIfornetworkandchannelI/Ointerfaces.FCtechnologysupportsHIPPI,IPI,SCSI,IP,ATMandotheradvancedprotocols.Itsbiggestfeatureistoseparatethecommunicationprotocolofthenetworkandequipmentfromthephysicaltransmissionmedium,sothatmultipleprotocolscanbetransmittedsimultaneouslyonthesamephysicalconnection.

ThehardwareinfrastructureofSANisFibreChannel,andtheSANbuiltwithFibreChanneliscomposedofthefollowingthreeparts:

1)Storageandbackupequipment:includingtape,diskandopticaldisclibraryWait.

2)FibreChannelnetworkconnectioncomponents:includinghostbusadaptercards,drivers,opticalcables,hubs,switches,bridgesbetweenFibreChannelandSCSI

3)ApplicationandManagementsoftware:includingbackupsoftware,storageresourcemanagementsoftwareandstoragedevicemanagementsoftware.

TheadvantagesofSAN:

1)Easynetworkdeployment;

2)High-speedstorageperformance.BecauseSANusesFibreChanneltechnology,ithashigherstoragebandwidthandstorageperformanceissignificantlyimproved.SAn'sfiberchannelusestheprincipleoffull-duplexserialcommunicationtotransmitdata,withatransmissionrateofupto1062.5Mb/s.

3)Goodscalability.AstheSANadoptsthenetworkstructure,theexpansioncapabilityisstronger.Theopticalfiberinterfaceprovidesaconnectiondistanceof10kilometers,whichmakesitveryeasytoachievephysicalseparationandstorageoutsidethelocalcomputerroom.

Comparisonofthreestoragemethods

Thebiggestfeatureofstorageapplicationsisthatthereisnostandardarchitecture.Thesethreestoragemethodscoexistandcomplementeachother,andtheyarealreadywellsuitedforenterpriseinformatizationapplications.

Fromthecomparisonofconnectionmethods,DASusesstoragedevicestodirectlyconnecttoapplicationservers,whichhascertainflexibilityandrestrictions;NASconnectsstoragedevicesandapplicationsthroughnetwork(TCP/IP,ATM,FDDI)technologyThelocationofserversandstoragedevicesisflexible.Withtheemergenceof10Gigabitnetworks,thetransmissionratehasbeengreatlyimproved;SANconnectsstoragedevicesandapplicationserversthroughFibreChanneltechnology,whichhasagoodtransmissionrateandexpansion.performance.Thethreestoragemethodshavetheirownadvantages,coexistwitheachother,andaccountformorethan70%ofthediskstoragemarket.ThepriceofSANandNASproductsisstillmuchhigherthanthatofDAS.Manyuserschooselow-efficiencydirect-attachedstorageinsteadofhigh-efficiencysharedstorageforpricereasons.

Objectivelyspeaking,SANandNASsystemscanalreadyusetechnologieslikethinprovisioningtomakeupfortheinflexibleshortcomingsofearlystorageallocation.However,beforetheyconsumedtoomuchtimetosolvethestorageallocationproblem,sothatenoughtimeforDAStogainafootholdinthedatacenterfield.Inaddition,SANandNASstillhavemanyproblemsthatcannotbesolved.

Storagepricetrap

Sometimesitisnecessarytoupgradethesystembyforklift,butalittlecarefulconsiderationduringtheprocurementprocesscanavoidpricetrapsthatmaybeencounteredinstorageprocurement.

Thepriceofstorageischanginguntoldly

Storageequipmentisatypicalwastefulexpenditurecausedbytechnologicalchanges,butitalsohasitsinevitabilityandnecessity.In2005,IntegratedDriveElectronics(IDE)wasmainlyusedforlow-enddatastorage,andSmallComputerSystemInterface(SCSI)harddisksweremainlyusedforhigh-endservers.IDEwasveryslow,untilitdevelopedintoanenhancedIDE,afterwhichSATAtechnologycameonthescene.SATAIII2015iscomparabletohigh-endstorageoptions—SerialLinkSCSI(SAS)—andatalowercost.

Allthesestoragedevicesusespinningharddrives,whichcannotcompetewiththeflashmemoryin2015.Flashmemorywasinitiallyusedasacamerastoragemedium,whichwasfragileandniche,butin2015ithasbecomethestoragemediumofchoiceformostdatacenterequipmentmanufacturers.

Hiddencosts

Evenifthehardwareisrelativelycheap,managementandmostrelatedtoolswillincreasethecostofstorage.

Toolsthatcanonlyidentifyphysicalarrayshavebeenabandonedbyvirtualization.Thosesoftwarethatcanhandlestorageinthevirtualizedworldfindthatvirtualstoragestillreliesonthesupportoftheunderlyingphysicaldriveplatform.

Thereisaneedforatacticalstrategyandtheneedtomaximizetheuseofexistingtechnologybeforethenexttechnicalforkliftupgrade.Buttacticaldecisionsarenotstrategies,andconflatingthetwocanleadITorganizationstothewrongtechnicaldirection.

Ifthecurrentstoragesupplierhasbeeninstillingthatyourflashstorageisveryfragileanditsavailabilityisunproven,thenitislikelythatyouhaveboughtalargeSASarrayasastrategicinvestment.Itusedtobethebeststorage,andyouhopeitcangivefullplaytoitsperformanceforalongtimewithoutdepreciatingtoomuch,butin2015thestrategyhasencounteredproblems.

TakingSASdrivefailureasanexample,thiswillcauseRAID6reconstructionandseverelyaffectperformance.Iftherequiredsizehasbeendiscontinued,itwillbecomedifficulttofindsparepartstoreplacethefaileddrive,andthearraycannotacceptdifferenttypesofdrives.Userswillcomplainthatallapplicationsareveryslow.Youwanttoaddaflashstoragelayertoimproveperformance,butfindthatthearraydoesnothaveaninterfacetosupportsolid-stateharddrives.

Thechoiceistobuyanewstorage,moveallthedataaway,andthenthrowawaytheoldsystem-thereisnoneedtoreplacethedriveatall,anditisnotevenworthsellingtorecoverthefunds.

BeforeconsideringupdatingtheITplatform,thinkahead-adecisionthatseemstobecorrectwillnotbesosureinthefuture.Understandthetactical/strategicoppositionandifyouneedalong-termsolution,youmusthavestandardsandcommercialization.

Askthesupplierhowtheexistingproductworkswiththeoldversion.Iftheproductssoldbythemanufacturerin2015arenotsocompatiblewiththeoldseries,itisverylikely-nomatterwhatthesalesrepresentativepromises-thisheraldsthenextforkliftupgrademoment.

Consultingsuppliersneedtoadheretosomestandards:dotheyinsistonkeepingabreastofmarketchangesinatimelymanner,anddotheirproductsfullysupportindustrystandards?Willtherebeinteroperabilityproblemswithothermanufacturers’productsifthesestandardsareexceeded?

Canothermanufacturersprovidecomplementstotheproductsyouarepurchasingtoincreaseaddedvalue?Communicatewiththesepartnersandthirdparties,andaskthemwhetheritiseasytorespondandchangewhenthesupplier'sproductchanges.

Killingthetrueculpritofdatacenterdatastoragecapacity

Theheterogeneityofdatacenterdatastoragearchitectureandcontrollersisoneofthemajorgoalsofstandardizedinfrastructuretosupportdifferentworkloads.obstacle.

Forallwishesandgoals,thecoreofthedatastoragesystemisproductization.However,therearestilldifferencesatdifferentlevelsinthebattletoachievetheinteroperabilityofdatastoragearraysfromdifferentvendors.

Distributedcomputingmeansthatdatacenterdatastoragemustinteroperatewithserversfromdifferentvendors,whichincreasestherequirementsfordatastoragearchitecturestandardization,andcloudcomputingpromotesgreaterprogressinstandardization.

Datastoragemanagement

Datacenterstoragecapacitymanagementhasalwaysreliedonarelativelyunchangedbasicdatastoragetechnology:traditionalmechanicalharddrives.Thereareonlyafewmanufacturersofmechanicalharddrives—WesternDigitalandSeagate,andHitachiandToshiba—harddrivesareessentiallyacommodity.

Theproblemneedstobesolvedbyrealizingthecollaborativeworkofarraysandcontrollersofdifferentbrands.Somecompanieshavepurchasedhigh-end,expensivestorage,suchasEMC'sSymmetrixVMAX,hopingtomanagetheentiredatastoragethroughasingletoolset.However,theoperationofthediskarrayiscontrolledbydedicatedsoftwareanddatastorageinthearraycontroller,whichisproblematicforcreatingafullyfunctionaldatastoragemanagementtool.

Datastoragevendors-IBMhasSANVolumeController,EMCusesVPLEX,HitachiDataSystems,HPandNetApparealltoutingtheirproprietarydatastoragemanagementtools,claimingtheirItcanrealizetheintegrationofvirtualstoragearchitecture.However,thesetoolsbasicallyonlysupportdatastoragesystemsoftheirownmanufacturers,andinmostcases,theyonlytargetsomeproducts.Endusersarelookingforrealdatastorage,high-functionheterogeneousdatastoragemanagementtoolstonoavail.

Cloudcomputingischangingourviewofdatastorage.Workloadsarebecomingmoreandmoremixed,anddatastorageneedstomanageobjects,files,andblockmodesaccordingtodifferentI/Orequirements.Nevertheless,tosupportcloudarchitecture,datastorageinfrastructuremustbeviewedasasingleresourcepool,andorganizationsneedtobeabletoautomaticallyadapttochangesinworkloads.Onlybyprovidinghighlystandardizeddatastoragetoolsisitpossibletoachievesuchafunction.Thisinitiativehasalreadybegun,butthereisstillalongwaytogo.

Flashdatastoragerescuesite

Standardizeddatacenterdatastoragecapacityisdifficulttocreateseparatelyonlythroughdiskstorage.Themediumreliesontheinteractionbetweenthediskplatters,andtheread/writestabheadrequiresanintelligentdiskcontrollertomediatetomanagetheneedsofdifferentworkloads.

Thedatamanagementmethodofflashdatastorageisdifferentfromthatofharddisk.Flashdatastorageisadirectaccesstothestoragearchitecture;thereisnoneedtosearchforthecorrectdiskareathroughthemagneticheadtoretrievedata,sothereisnodelay.Theadvantageofdatastoragemanagementspeedmeansthatflashmemorycanbeappliedtodifferentworkloadtypesinthesamearray.Itisalsomoreunifiedacrossdifferentvendors'datastorageproductstoachievevirtualization.

Finally,standardizeddatastoragemaybearealcommitment,notjustafocusofdiscussion-butitisstillfaraway.

Datastoragevendorsstillhavemanydifferentwaystopromotethedeploymentofflashmemory.Manyestablisheddatastoragevendorspeddledthroughahybridapproach:addingaseparateflashmemorylayerinfrontofthediskarray.Problemsmayarisewhenthedatastoragerequiredbytheworkloadisnotinthisflashlayer,becausethecontrollerneedstopullthesedatastoragefromtheharddisk.Thismakescertaindatastorageoperationsslowerthanpureharddiskarrays.

Anecessarysteptomaximizetheinvestmentindatastoragecapacityofexistingdatacentersistocascadepureflashmemoryanddiskarraysystems.Nonetheless,theseexistingtraditionalarrayscanbecometroublemakerswhenbuildingasinglemanagementlayer.EMCViPRdatastoragevirtualizationproductshavedemonstratedtheircommitmenttoprovidegreatercontroloverthehybriddatastoragearchitecture.

All-flasharraysarebundledtogetherinthefiercecompetitionofhybriddatastorage.Flashdatastorage,suchasPureStorage,ViolinMemoryandNimbleStorage,providesintelligentsoftwaretominimizedatastoragevolumes,andprovidesanadvanceddatastoragemanagementsystemtomanagetheentirevirtualizedenvironment.

DataStorageSystemConvergence

WhentheConvergedInfrastructure(CI)systemencountersclouddatastoragemanagement,itisalittlemessy.

Nutanix-asupplierthatstartedasadatastoragespace,providessuperCIplatformservices,includingadvanceddatastoragemanagementsoftware.IBM'sPureFlexsystemandPureDatasystem,Dell'sPowerEdgeFX2system,HP'sConvergedInfrastructure,andotherdatastorageproductsalsoprovidevariousmethodstoachievetheintegrationofdirectdatastorageandCIsystems,notonlyexistingarraysornewarraysAllaresteppinguptheintegrationofexpansionandCI.

Thereisanotherwaytoincreasethespeedofserver-sidedatastorageconnections,suchasflashdatastoragewithPCIeinterface.IBMhasdevelopedamethodforinternalconnectionofitsownsystem,whichcanfurtherspeedupdatastorage.ThisCAPIconnectoronceagainbringsaproprietaryproblem-itwilldependonwhetherIBMwillallowtheconnectortomaintainahighlevelofunifiedcollaborationwithothervendors'datastoragesystems.Convergedsystemsmuststillpoolresourcestoshareanduse.Thiswillrequiremoreadvanceddatastoragetoolsthanwecanseetosupportit.