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Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
NexentaStor&NexentaFusionUnifiedBlock&FileSoftware-DefinedStorage
ProductGuideNovember2017
NexentaStorProductGuide
2 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
TableofContents
1 NexentaStorOverview......................................................................................................51.1 IntroductiontoNexentaStorSDS..............................................................................................................................51.2 NexentaStorSoftwareArchitecture.......................................................................................................................71.3 NexentaStorHighAvailability................................................................................................................................101.4 NexentaStorReferenceArchitectureandAppliances..................................................................................111.5 NexentaStorLicensing..............................................................................................................................................121.6 BenefitsofNexentaStorSoftware-DefinedStorage......................................................................................141.7 WheretoFindMoreInformation.........................................................................................................................152 DeploymentScenarios&UseCases.................................................................................162.1 UseCases.........................................................................................................................................................................162.2 DeploymentScenarios...............................................................................................................................................172.3 VMwareIntegration...................................................................................................................................................182.4 OpenStackIntegration..............................................................................................................................................182.5 StretchClustersandMetroHAConfigurations...............................................................................................19
3 UnifiedBlockandFileServices........................................................................................203.1 StoragePoolingArchitecture.................................................................................................................................203.2 PerformanceManagement......................................................................................................................................213.3 DeviceFailureHandling...........................................................................................................................................223.4 DataatRestEncryption............................................................................................................................................233.5 FileSystemsandSharedFileServices................................................................................................................233.5.1 SharedFileServices..................................................................................................................................................243.5.2 AccessControlLists..................................................................................................................................................243.5.3 Quotas,ReservationsandCapacityManagement.......................................................................................243.5.4 StorageQoSForFileServices...............................................................................................................................25
3.6 VolumesandSharedBlockServices....................................................................................................................263.6.1 VolumeGroups...........................................................................................................................................................263.6.2 iSCSIBlockServices..................................................................................................................................................263.6.3 FibreChannelBlockServices...............................................................................................................................27
NexentaStorProductGuide
3 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
4 NexentaStorDataProtection..........................................................................................284.1 InstantSpaceOptimizedSnapshotsandClones............................................................................................284.2 SnapshotServices........................................................................................................................................................294.3 HighPerformanceReplicationOverview..........................................................................................................294.4 LicensingConsiderationsforHPR........................................................................................................................304.5 ScheduledReplicationServices.............................................................................................................................314.6 ContinuousReplicationServices..........................................................................................................................324.7 Multi-Destination........................................................................................................................................................334.8 MovingDatasetToandFrom3rdPartyOpenZFSSystems........................................................................33
NexentaStorProductGuide
4 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
PrefaceCopyright,Trademarks,andComplianceCopyright©2017NexentaSystems™,ALLRIGHTSRESERVED
Notice:Nopartofthispublicationmaybereproducedortransmittedinanyformorbyanymeans,electronicormechanical,includingphotocopyingandrecording,orstoredinadatabaseorretrievalsystemforanypurposewithouttheexpresswrittenpermissionofNexentaSystems(hereinafterreferredtoas“Nexenta”).
Nexentareservestherighttomakechangestothisdocumentatanytimewithoutnoticeandassumesnoresponsibilityforitsuse.NexentaproductsandservicesonlycanbeorderedunderthetermsandconditionsofNexentaSystems’applicableagreements.Allofthefeaturesdescribedinthisdocumentmaynotbeavailablecurrently.RefertothelatestproductannouncementorcontactyourlocalNexentaSystemssalesofficeforinformationonfeatureandproductavailability.Thisdocumentincludesthelatestinformationavailableatthetimeofpublication.
Nexenta,NexentaStor,NexentaEdge,andNexentaConnectareregisteredtrademarksofNexentaSystemsintheUnitedStatesandothercountries.Allothertrademarks,servicemarks,andcompanynamesinthisdocumentarepropertiesoftheirrespectiveowners.
NexentaStorProductGuide
5 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
1 NexentaStorOverview
NexentaStoristheindustry’sleadingsoftware-definedstorage(SDS)platform,deliveringfull-featured,enterprise-classunifiedblockandfilestorageservices.Asofversion5,NexentaStorisusedbythousandsofcustomersinconfigurationsrangingfromtensofterabytestomultiplepetabytesasareplacementforlegacystorageareanetwork(SAN)andnetworkattachedstorage(NAS)hardwareappliances.
Unlikehardwareappliancesfromtraditionalstoragevendors,NexentaStorisdeliveredassoftwarethatcaneitherbedeployedonbaremetalindustry-standardx86serversconnectedtosharedSASstorageenclosuresanddevices,orasavirtualmachineonawidevarietyofhypervisorsonpremiseorinpublicclouds.NexentaStor5incorporatesastateoftheartmanagementframeworkexposinganexhaustivesetofdeveloperfriendly,self-documentingRESTAPIsthatarethefoundationforallusermanagementinterfaces(CLIandGUI)andecosystemplugins.NexentaFusionshipswithNexentaStor5andprovidesasinglepaneofglassmanagementinterfaceformulti-systemdeployments.
Beingdeliveredassoftwareonlygivescustomersnewlevelsofflexibilityandperformance,eliminateshardwarelock-in,significantlyreducesstoragecosts,andgenerallysimplifiesstoragemanagementandscaling.
1.1 IntroductiontoNexentaStorSDSNexentaStorprovidesstandardfile(NFSandSMB)aswellasblock(FCandiSCSI)protocolservices.Thesoftwareisdeployedasafullstorageoperatingsystemonstandardx86baremetalservers,orinvirtualmachinesinprivateorpubliccloud.NexentaStorcanberuninsingle-nodeconfigurationsoninternaldevicesorindual-nodehigh-availability(HA)clusterconfigurations,withSAS-connectedsharedbackenddevices.
Figure1-1: NexentaStorAppliancesConfiguration
NexentaStorProductGuide
6 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
NexentaStorbuildsontheopensourceOpenZFSfilesystemtodeliverhigh-performance,enterprise-classdataservicesthateffectivelycompeteandwinagainstlegacystorageappliancevendors:
Figure1-2:NexentaStor5FeatureSupport
Protocols File:NFSv3,NFSv4,SMB1.0,SMB2.1,SMB3Block:FibreChannel,iSCSI
Configurations Singlenode–x86baremetalDual-nodeHighAvailabilityclusters–x86baremetalMetroHAStretchedclusters–x86baremetalVirtualStorageAppliance–VMwareESXi,KVMAmazonWebServices
DataManagement All-Flash,Hybrid,orAll-DiskpoolsRAID10,N+1,N+2,N+3OpenZFSend-to-enddataintegrityUnlimitedsnapshots&clonesUnlimitedfilesystemsizeHighperformanceinlinedatareductionThinprovisioningStorageQualityofServiceSnapshotbasedScheduledReplicationContinuousAsynchronousReplication
Management SelfdocumentingRESTAPI,CLI,SNMPNexentaFusion(HTML5based)
ClientOSSupport VMwareESXi,MicrosoftWindows,CentOS,RHEL,Ubuntu
EcosystemIntegration SMB3ODXforMicrosoftHyper-VVMwareVAAIBlockVMwareVirtualVolume(VVOL)2.0VMwarevCenterPluginVMwareSiteRecoveryManagerOpenStackCinder&ManilaDockerVolumePluginKubernetesPersistentVolume
NexentaStorProductGuide
7 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
ThismaturesetoffeatureshasallowedNexentatosuccessfullysellintoawidevarietyofmarketverticalsandusecases,fromhigh-performancelow-latencyall-flasharrayssupportingvirtualenvironmentsandbusiness-criticalapplications,allthewaytolarge-scalecost-optimizedbackupandarchiverepositories.
ThetypesofconfigurationsandtargetusecasesforNexentaStorareshowbelow:
Figure1-3: NexentaStorUseCases
Theabilitytoselecttherighthardwareconfigurationfortherightworkloadgivescustomersmaximumflexibility.Havingthesamesoftwarestackrunningonhigh-performanceall-flash,balancedhybridandcost-optimizedbackupandarchivesetupssimplifiesdatamovementacrosstiersandmanagementofthefullstorageinfrastructure.
1.2 NexentaStorSoftwareArchitectureNexentaStor5buildsontheopensourceOpenZFSfilesystemforitscoredataservicesandcomplementsitwithhighperformanceblockandfileservices,high-availabilityclustering,kernelbasedmulti-sitereplicationandtheNexentaManagementFramework(NMF).
Asshowninthefigurebelow,NMFprovidesatightcoverontheunderlyingstorageoperatingsystemandhandlesallprovisioningandmanagementoperations.Fromauserperspective,NMFpresentsanexhaustiveself-documentingRESTAPIthatprovidesaconsistentfoundationforthesystem’sCommandLineInterface(CLI),theNexentaFusiongraphicaluserinterfaceandallsupportedecosystemplugins.
NexentaStorProductGuide
8 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
Figure1-4: NexentaStorHighLevelArchitecture
NexentaStor5benefitsfromallthescalability,performance,andreliabilityimprovementsinthecoreplatformthatwereimplementedoverthelastfewyearsinNexentaStor4.NexentaStor5alsoincorporatesanumberofnewandenhanceddevicedrivers,addingsupportfor25Gb/sand40Gb/sEthernetinterfaces,aswellas32Gb/sFibreChannelHBAs.
TheNexentaManagementFrameworkwasfirstintroducedwithNexentaStor5.0andfullyreplacedthelegacyNexentaManagementServer(NMS),NexentaManagementConsole(NMC),andNexentaManagementView(NMV)thatwerepartofNexentaStor4.xandallpreviousreleases.
Bydesign,NMFisahigh-performance,multi-threaded,fault-tolerantmanagementplanethatprovidesastreamlinedandsimplifiedstorage-centricmanagementexperience.BuildingtheNexentaStorCLIaswellasallmanagementproductsontopoftheNMFRESTAPIensuresthatalloperationsandallstatisticsavailablethroughtheCLIandGUIaresupportedviatheRESTAPI.
NexentaStorProductGuide
9 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
TheNexentaStorRESTAPIisself-documentingandprovidesaninteractiveSwaggeruserinterfacefordevelopersandtechnologypartnerslookingtobuildstorageautomationandorchestration.
Figure1-5: NexentaStorRESTAPIManagementScreen
DaytodaymanagementoperationsareaccomplishedusingtheNexentaFusionmanagementserver,freelyavailablewithanyNexentaStor5license.NexentaFusioncomplementsanyNexentaStor5deploymentandprovidesasinglepaneofglassGraphicalUserInterfaceformultipleNexentaStorappliances.NexentaFusionisavailableasaVMwareOVAandasaDockercontainerforsimpledeploymentonanyLinuxhost,physicalorvirtual.Itincorporatesintuitiveworkflowsforallprovisioningandfaultmanagementtasksanddeliversadvancedanalyticsdashboardsfordetailedmonitoringandtroubleshooting,storinguptotwoyearsofhistoricalservicedata.
Figure1-6: NexentaFusionManagementScreen
NexentaStorProductGuide
10 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
1.3 NexentaStorHighAvailabilityNexentaStorhighavailability(HA)allowsyoutoconfiguretwoNexentaStornodestoprovideredundantaccesstostoragepools.Active-passive(twoNexentaStornodes,onepool)andactive-active(twonodes,twopoolsormore)configurationsaresupported.Ifanodeisunabletodeliverstorageservicesforsomereason,theothernodeautomaticallytakesover.
Technically,aNexentaStorHAconfigurationconsistsofanHAclusterwhereoneormoreHAservicesarerunning:
• AnHAclusterisapairofNexentaStornodesthatshareaccesstobackendstoragedevices,havenetworkconnectivitytoeachother,andonwhichthehighavailabilityfeatureisenabled.
• AnHAservicespecifiestheVirtualIP(VIP)address(es)orFibreChannelportsfortheHAcluster,thestoragepool(s)tobeprotected,andwhichofthenodesinitiallyprovidesclientsaccesstothestorage.
TofacilitateHAconfigurationforfileandiSCSIservices,eachnodeshouldhaveatleastonestaticIPaddressassignedtoit,andeachVIPshouldhaveitsownstaticIPaddress.
Figure1-7:ExampleNexentaStorHighAvailabilityConfiguration
Inthisexample,Node-AandNode-BcompriseanHAcluster.Therearetwostoragepools,Pool-AandPool-B,thatconsistofbackendstoragedevicesthatareaccessibletobothnodesintheHAcluster.TherearetwoHAservicesinthisconfiguration:onethatprovidesaccesstoPool-AusingVIP-AandanotherthatprovidesaccesstoPool-BusingVIP-B.Inthisexample,Node-AservesasthebackupforPool-B,andNode-BservesasthebackupforPool-A.
Node-AandNode-Bexchangestatusinformationusinganumberofdifferentnetworkandstorageheartbeatmechanisms.Ifalloftheheartbeatmechanismsaredisruptedforagivenlengthoftime,thenthemainnodeisconsideredtohavefailed,andthebackupnodetakesover.Inthisexample,failureofNode-AwouldleadtoNode-BtakingoverPool-AandVIP-A,andfailureofNode-BwouldleadtoNode-AtakingoverPool-BandVIP-B.
Oncethefailednodeisrestored,itcantakebackitsstoragepool.Youcanconfigurethistooccurautomaticallywhenthenodecomesbackonline,oryoucandothismanually.
NexentaStorProductGuide
11 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
1.4 NexentaStorReferenceArchitectureandAppliancesWhilethematurity,flexibilityandcost-effectivenessofNexentaStorsoftware-definedstoragemakeitattractiveforabroadsetofEnterpriseusecases,meetingtheneedsofEnterprisecustomersalsorequiresspecificattentiontodeploymentandsupportability.
Enterprisecustomersgenerallyexpecttohave“onethroattochoke”whenitcomestosoftwareandhardwaresupport.ThisiswhyNexentaworkscloselywithhardwarepartnersandserverOEMstocertifyfullstackReferenceArchitectures(RAs)thataddressall-flash,hybridandall-diskstoragerequirementsandscalefromtensofterabytestomulti-petabyteappliances.
Figure1-8: ReferenceArchitectureExamples
Theseend-to-endsolutionsaredeliveredthroughserverpartnerssuchasCisco,DellEMC,Ericsson,LenovoorSupermicrowithmanyprovidingfullstacksupport,takingfirstcallonbothsoftwareandhardwareandprovidingaseamlesssupportexperiencetoNexentaStorusers.
Inadditiontoreferencearchitectures,aselectsetofserverOEMsofferNexentaStorbasedhardwareapplianceswherethesoftwareispre-loadedandpre-configuredinmanufacturingprovidingaturn-keyhardwareapplianceexperiencetoendcustomers.
Certifyingareferencearchitectureentailsthefollowing:
• WorkingwiththehardwarepartnertocreateNexentaskusforthespecifichardwareconfigurations,explicitlyspecifyingCPU,DRAM,HBAandNICcomponentsandfirmware,todelivertherightperformanceandcapacityscaling
• Performingextensivehardwareandsoftwareinteroperabilitytestingtoensurethatthesolutionwilloperateandperformasexpectedinproductionenvironments
• DevelopinghardwarespecificchassismanagementpluginsforNexentaStorandNexentaFusiontosimplifyday-to-dayoperationsrelatedtohardwaremanagement,devicereplacement,etc.
NexentaStorProductGuide
12 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
Figure1-9: NexentaFusionChassisManagementforSupermicroAppliance
FormoredetailsonNexentaStor5referencearchitecturesandappliances,pleaseseetheNexentaStor5HardwareCompatibilityList.
1.5 NexentaStorLicensingNexentaStor5isavailableasanEnterpriseEditionorCommunityEdition:
• NexentaStorEnterpriseEditionissoldasaperpetualsoftwarelicensebasedonrawcapacityundermanagement(measuredinTB).Supportandservicesaresoldseparately.Pricingistieredontheamountofrawcapacityrequiredforasystem,withalargerconfigurationgettingalowerpriceperGBthanasmallerone.
TheEnterpriseEditionincludesallcorestoragefunctionalitysuchassnapshots,clones,inlinedatareduction,softwareRAIDandsnapshotbasedscheduledreplication.ItalsoincludestherighttouseNexentaFusionastheGraphicalUserInterfaceforthesystemrunningthatlicense.Additionaloptionsaresoldonaper-nodebasisandincludefeaturessuchasHigh-AvailabilityCluster,MetroHA,ContinuousReplicationorFibreChannelsupport.
• NexentaStorCommunityEditionisalimited-functionality,limited-capacity,freeversionofthesoftwarethatcanbeusedfornon-productiondeployments.OutsideoftheonlineNexentaCommunityforums,nosupportservicesareavailableforNexentaStorCommunityEdition.ANexentaFusionservercanmanageatmostoneNexentaStorCommunityEditionappliance.Formoredetails,seetheonlineNexentaCommunityforums.
NexentaStorProductGuide
13 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
Figure1-10:NexentaStorSoftwareLicenses
LicenseType TimeLimit CapacityLimit SeparatelyLicensedOptions
EnterpriseEdition None Variable • HighAvailability Cluster• HPRContinuousReplication• FibreChannelTarget• MetroHA
Trial 45days Variable TrialperiodincludesEnterpriseEditionoptionalfeatures
CommunityEdition None 10TBAllocated None
NexentaStor5implementsasimplelicensingenginethatseamlesslyintegrateswiththenewcustomerlicenseportalsonNexenta.com.ActivatingalicenseonaNexentaStor5appliance(singlenodeorHAcluster)isassimpleasenteringtheactivationtokenprovidedbythecustomerlicenseportalandlettingthesystemautomaticallyregisteranddownloadalicensefile.
ThefollowingfeaturescanbeaddedtoanEnterpriseEditionlicense:
• High-AvailabilityCluster–ConfiguresapairofphysicalserverstorunasahighlyavailableNexentaStorappliance,providingredundantaccesstosharedstoragepools.IfoneoftheNexentaStornodesshouldfail,allstorageservicesareseamlesslyfailedovertotheothernode.Seesection1.3formoredetails.
• ContinuousReplication–TheEnterpriseEditionlicenseincludesscheduledreplicationservicestoaremoteappliance,withaminimumscheduleofareplicatedsnapshotevery15minutes.TheContinuousReplicationoptionallowsscheduledreplicationasoftenaseveryminute.ThisoptionalsounlocksthecontinuousasynchronousreplicationfunctionalitythatallowsasclosetozeroRecoveryPointObjective(RPO)aspossibleoveranydistance,withoutaffectingapplicationperformance.Seesection4.6formoredetails.
• FibreChannelfunctionality–AllowsyoutoconfigureFCtargetsontheapplianceandserveLUNsoverFibreChannel.
• MetroHA–EnablesNexentaStortodeliverzeroRPOcontinuousavailabilitydisasterrecoverybetweensitesinthesamemetroarea.Seesection2.5formoredetails.
ContactNexentaSystemsforinformationonpurchasingalicenseforthesoftwareandindividualfeatures.
NexentaStorProductGuide
14 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
1.6 BenefitsofNexentaStorSoftware-DefinedStorageWithitsperformance,enterprise-gradereliabilityandfeatureset,NexentaStorisuniqueinthemarketinitsabilitytobringtheflexibility,agilityandcostsavingbenefitsofSoftware-DefinedStoragetotraditionalenterprisestorageenvironments.
Morespecifically,NexentaStordeliversthefollowingbenefits:
• Nocompromise.NexentaStorincludesalltheadvancedstoragefunctionalitythatcanbeexpectedofhigh-end,enterprise-classstoragearrayssupportingunifiedblockandfileservices.Thesolutionalsosupportshighlydifferentiatedfeaturessuchashigh-performanceinlinedatareductionforall-flashconfigurations,tripleparityRAIDforlargearchivesetups,continuousreplicationfornearzeroRPOdisasterrecoveryscenarios,andunlimitedfilesystemsizes.
• Greatperformance.NexentaStorreferencearchitecturesmakeuseofthelatesthardwarecomponentsandgenerallytakeadvantageoflargeramountsofDRAMintheNexentaStornodesthanistypicallyfoundintraditionalstorageappliances.Thecombinationofhigh-performancesoftwareandhigher-performancehardwarecomponentsintheNexentaStorreferencearchitecturestranslatesintosolutionsthatgenerallyoutperformthecompetition.
• Totalcontrol.CustomersrunningNexentaStorsolutionseffectivelyareinfullcontrolofwhattodeployfortheirstorageneedsandwhentorefreshtheirstorageinfrastructure.Ratherthanhavingatraditionalstorageappliancevendordictatewhenaparticulararrayneedstobereplaced,NexentaStorcustomersgettochoosewhentorefreshthestandardx86servercomponentssupportingtheirstorageinfrastructure.HavingtheoptiontorunaNexentaStorapplianceforfiveorevensevenyearsonthesamehardwarecantranslateintosignificantcostsavingsoverthelifeofasystem.
• Simplifiedmanagementandscaling.NexentaStor5implementsadeveloper-friendly,self-documentedRESTAPIforeaseofautomationandorchestration.Formoretraditionaloperationalenvironments,NexentaFusiondeliversamodernandintuitivegraphicaluserinterface(GUI)forallprovisioningandmonitoringworkflows.
• Lowertotalcostofownership.Byrunningonstandardx86servers,NexentaStorallowscustomerstoacquirehigh-performance,enterprise-gradestoragesolutionsatindustry-standardx86serverprices,avoidingthetypicalhighmarginchargedbytraditionalstorageappliancevendors.Furthermore,NexentaStor’sperpetualsoftwarelicensesallowcustomerstosimplyrepurposelicensesandsaveoverthelongrunashardwarerefreshesonlyincurhardwarecosts,notsoftwarecosts.
NexentaStorProductGuide
15 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
1.7 WheretoFindMoreInformation
Document Purpose
QuickStartGuides ThesedocumentsprovidebasicinformationaboutessentialfunctionalityofNexentaStorandconciseprocedurestogetyouupandrunningasquicklyaspossible.
Thequickstartguidescoverthefollowingtopics:• NexentaStorandNexentaFusioninstallation• NexentaStorCLIConfiguration• NexentaStorCLIReferenceGuide• NexentaStorHighAvailability• NexentaStorHighPerformanceReplication• NexentaStorRESTAPI• NexentaStorData-at-RestEncryption• NexentaStorvCenterplugin• NexentaStorVVOLAdministration
NexentaStorCLImanualpages Enter<command> -h forhighlevelinformationonsub-commandsandoptionsandman <command> togetdetailedusageinstructions
NexentaFusiondocumentation NexentaFusion’sonlinehelpprovidesstep-by-stepproceduresforcommonconfigurationandmonitoringtasks.
Additionaldocumentation:• NexentaFusioninstallation• NexentaFusionUserGuide
Releasenotes High-leveloverviewofnewfunctionalityinagivenreleaseanddetailedreviewofresolvedandknownissues.
TheNexentaStorquickstartguidesandNexentaFusiondocumentationareavailableonlineinPDFandHTMLformatfromnexenta.comat:https://nexenta.com/products/documentation
NexentaStorProductGuide
16 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
2 DeploymentScenarios&UseCases
2.1 UseCasesNexentaStorsoftwareissuccessfullyusedbythousandsofcustomersoverawiderangeofusecases,fromhighperformancetransactionaldatabasestoprivatecloudandcost-optimizedverylarge-scalebackupandarchive.Theabilitytousethesamestoragesoftware,withthesamerichfeaturesetandmanagementinterfacesandAPIsacrossalltheseworkloadsenablescustomerstomassivelysimplifytheirstorageinfrastructure.
Figure2-1:TypicalNexentaStorUseCases
All-flashconfigurationsareidealforhighperformanceapplications,databasesandcloudhostingusecases.NexentaStoronall-SSDconfigurationsprovideshighperformance,lowlatencystorageservices.All-flashNexentaStorreferencearchitecturecanhitverylow$/GBpricepointsthatmakeall-flashstoragecost-effectiveforalargershareofapplications.Combiningthelowcapexofsoftware-definedonall-flash(builtonindustrystandardx86serversandSSDs)withthelowopexbenefitsofall-flashstorageingeneral(easiertorun,morereliable,lesspower,lessspace)hasallowedanumberofNexentacustomerstofullystandardizeonall-flashsystems,deployingmultiplepetabytesofall-flashNexentaStorforbothblockandfileservices.
HybridconfigurationscombineafewSSDsforwriteloggingandreadcachingwithNL-SASHDDsforlong-termdatastorage.Theseconfigurationsarepopularforprivatecloudandthewidevarietyofapplicationsrequiringunstructureddatastorage,NASservicesandfull-featuredNFSandSMBservices.Theseconfigurationsoftenscalefromhundredsofterabytestopetabyteswithsingleordualparityraidtooptimallybalancecostandperformancerequirements.
All-Diskconfigurationsareidealforlowcostbackupandarchiveusecases.Dependingonthebackupsoftwareused,customersleverageNexentaStorFibreChannel,iSCSI,NFSorSMBservices.Inthisusecases,systemsscaletomulti-petabytes,withlarge10TBor12TBHDDsandtripleparityraid.Tofurthersimplifydatamanagement,fewverylargefilesystemsaregenerallyconfigured,fromhundredsofTBtosingledigitPBscale.NexentaStorbuilt-inOpenZFSdataintegrityprotectionmechanismsensurethatfaithfullong-termdataretentionandthesoftware’sadvancedremotereplicationfunctionalitycanbeusedformulti-sitedisasterrecoveryconfigurations.
NexentaStorProductGuide
17 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
2.2 DeploymentScenariosANexentaStor5appliancebyitselfcanbemanagedviaCLIorRESTAPIs.TomanagetheapplianceviaGUI,itmustberegisteredonaseparateNexentaFusionserver,withaVMwarevCenterplugin,orboth.
AtypicalcustomerdeploymentincludesoneormoreNexentaStorappliancesmanagedbyasingleNexentaFusionserver,providingasingle-pane-of-glassGUI,asshownbelow.NotethattheNexentaFusionservermustbedeployedonadedicatedLinuxhost,oradedicatedLinuxvirtualmachine.
Figure2-2: NexentaStor5DeploymentScenarios
ForVMwareenvironments,NexentaStor5baremetalappliancescanbeusedtoprovidehigh-performanceFC,iSCSI,orNFSdatastorestovSphere.NexentaStor5canalsobedeployedasvirtualappliances,inVMwarevirtualmachines.BothbaremetalandvirtualizedNexentaStor5deploymentscanbefullymanagedviatheNexentaStor5vCenterplugin.
ThedeploymentscenariodepictedontherighthandsideofFigure2-2isafastgrowingusecaseforNexentaStorSDSinscenariosthatrequiretrueenterpriseclassfileservicesonhyper-convergedinfrastructure(e.g.NutanixorVMwarevSAN)andinenvironmentsrequiringadvancedmulti-tenantfileservices.Inthese,NexentaStorSDSissimplydeployedinvirtualmachines,consumingvmdksforbackendstorage.ManagementcanbeorchestratedthroughtheNMFRESTAPIs,CLI,orthroughthevCenterpluginwhichisitselfmulti-tenantcapable.
NexentaStorProductGuide
18 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
2.3 VMwareIntegrationEcosystemintegrationisanimportantbenefitofNexentaStorportfolio.NexentaStor5supportsVAAIforblockservices,andcomeswithanewVMwarevCenterPluginthatenablesVMwareadministratorstoperformadvancedstoragemanagementandstorageoperationtasksdirectlyfromvCenter.
Figure2-3: vCenterPluginApplianceDashboard
NexentaStor5alsosupportsVMwareVirtualVolumes(VVOL)overNFSprotocolendpointsforscalability.NexentaStor5.1alsoaddssupportforVMwareSiteRecoveryManagerwithNexentaStor5HighPerformanceReplication.
2.4 OpenStackIntegrationNexentahasbeenanearlyandactivememberoftheOpenStackstoragecommunity,buildingitsfirstsetofCinderdriversfortheOpenStackEssexrelease,allthewaybackinApril2012.AstheOpenStackplatformhasmatured,sohasNexentaStorintegrationwithNexentaStor5supportingCinderoveriSCSIandNFSprotocols,aswellasManilastorageservices.
Figure2-4: OpenStackCinderoveriSCSIorNFS
NexentaStorProductGuide
19 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
2.5 StretchClustersandMetroHAConfigurationsForapplicationsthatrequirecontinuousoperations,NexentaStorMetroHAdeliverscontinuousavailability,synchronousmirroringandzeroRPOdisasterrecovery.ThesolutioncanbedeployedbetweensitesconnectedviaastretchedFibreChannelSANonthesamecampusorinthesamemetroarea,overdistancesupto50miles/80km.
Functionally,NexentaStorMetroHAstretchesaNexentaStorHAclusteracross2sites,withoneNexentaStorheadnodeineachsite.SASbackendstorageenclosuresinbothsitesareconnectedusinghighperformanceATTOTechnologyXstreamCOREFC75xxControllerstoasharedstretchedFibreChannelFabric.TheNexentaStorsoftwaremanagesthisFibreChannelbackendstorageandsynchronouslymirrorsdataacrossbothsitestoensurezerodatalossintheeventofadevice,nodeorsitefailure.
Thesolutionprovidesautomaticfailoverforclear-cutfailurescenariosandoperatordrivensitefailoverforsitewidedisastersituations.
Figure2-5:MetroHAwithFourATTOXstreamCoreControllers
NexentaStorProductGuide
20 Copyright©2017NexentaSystems,ALLRIGHTSRESERVEDwww.nexenta.com
3 UnifiedBlockandFileServices
3.1 StoragePoolingArchitectureNexentaStorSDSdeliverstrueunifiedblockandfilestorageservices.Physicalcapacityisorganizedinlogicalpoolsofstoragethatcansupportbothfilesystemsandblockvolumesconcurrently.AsingleNexentaStornodewithasinglebackendpoolcanthusconcurrentlydeliverblockandfileservicestoclientapplications.
NexentaStor5buildsonOpenZFSforitscoredatalayer.InatypicalNexentaStorHAcluster,thephysicalcapacitywillbeorganizedinoneortwostoragepools.Eachstoragepoolisacollectionofvirtualdevices(vdevs),whicharethemselvesmadeupofphysicaldevicesthatareconnectedtotheNexentaStornodes.NexentaStorbuildsonOpenZFStoprotectdataagainstsilentdatacorruption,providingstrongdataintegrity,automatedself-healing,andadvancedsoftware-baseddataprotection.
Selectingtherightpoolconfigurationboilsdowntobalancingthefollowing3items:
• Resiliencetodevicefailure(s):NexentaStorvdevscanbeconfiguredasmirrors,orwithsingleparity,dualparityortripleparityprotection.Apoolwithmirrorvdevscansustainasingledevicefailurepervdev.Itishoweverexposedtodatalossintheeventofadouble-failureinthesamevdev.Largerphysicaldevicestranslateintohigherrisksofhittingadoublefailureinagivenvdev.ThisisonereasonwhyNexentabestpracticesusedualparityconfigurationsorhigherforpoolsoflargeHDDs.
• Usablecapacity:apoolwithmirrorvdevswilluse50%ofrawcapacityinparityoverheadwhileapoolwith(4+2)dualparityvdevswillonlyspend30%ofrawcapacityonparityoverhead.Giventhesamerawcapacity,the(4+2)poolwillprovidemoreusablecapacity.
• Performance:ignoringtheeffectsofZIL,SLOG,ARCandL2ARC,alldatastoredinapoolisautomaticallystrippedacrossthesetofvdevsthatmakeupthepool.Morevdevsinapoolgenerallytranslateintohigherpoolperformance,particularlyforrandomIOworkloads.Putdifferently,giventhesamenumberofphysicaldevices,apoolwithmirrorvdevswillgenerallydelivermoreIOPSthanapoolbuiltwith(4+2)vdevs.
Figure3-1: NexentaStorStoragePools
TheexampleaboveshowsaNexentaStorHAclusterwith2hybridpools.PoolAisconfiguredwithmirrorvdevsandSSDbasedmirrorwritelog(slog)andreadcache(l2arc),whilepoolBisconfiguredwith(4+2)dual-parityvdevsandSSDbasedmirrorwritelog.
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Filesystemsandblockvolumesarethencarvedoutofeachlogicalpool.Alldatastoredinapoolisautomaticallystripedacrossallvdevsinthepoolformaximumperformance.Thisallowsanydataset(filesystemorvolume),largeorsmall,togetaccesstothefullperformancecapabilityofthebackendpool.
NexentaStorappliancestypicallyrunwithafewlargepools(potentiallyscalinguptopetabytes)supportinglargefilesystems.Beingabletoscalepoolsandfilesystemsizesminimizesthenumberoflogicalentitiesthatneedtobemanagedandgenerallysimplifiesstoragemanagement.
Tosimplifysystemconfiguration,NexentaStor5supportsanewcreate-autofunctionthroughbothCLIandNexentaFusionthatautomaticallycreatespooldatavdevsbasedonuserprovidedcriteria.Forexample,usingthisfeatureausercanspecifyautomatedcreationofa“poolofRAID-Z2(4+2)vdevsacross1204TBHDDsacross3enclosuresencl_A,encl_Bandencl_Cwithenclosure-levelredundancy”.Thesystemtakescareoflayingoutallthevdevsintherightwayandautomatestheentiresetup.
3.2 PerformanceManagementNexentaisalongtimecontributortoOpenZFSacrossarangeofareascoveringdatamanagement,scalability,reliability,failuremanagementandperformance.NexentaStor5supportspoolsofSASSSDs,SASHDDs(generallyNL-SAS)andNVMeSSDs.Combiningmodernx86hardware,largeamountsofDRAMandfastSSDswithOpenZFSallowsNexentaStorhybridappliancestogenerallyout-performlegacystoragehardwareappliances.
OpenZFSwasspecificallydesignedtodeliveroptimalperformanceandavailabilityfromcommodityhardware.ItiswellknownforitshybridpoolperformancecapabilitiesanditsinnovativeuseofZFSIntentLog(ZIL),flashbasedsecondarylogdevices(SLOG),DRAMbasedreadcache(AdaptiveReplacementCache-ARC)andlargesizeflashbasedlevel2reachcache(L2ARC).
WhileextensiveinformationcanbefoundonlineontheinnerworkingsofOpenZFS,itisworthwhiletocalloutthefollowingwhenitcomestoperformanceandhybridpools:
• NexentaStormakesoptimaluseofallavailableDRAM.DRAMisprimarilyusedforreadcachingandtheAdaptiveReplacementCache(ARC).ARCconcurrentlyimplements2cachingalgorithmstooptimallyallocatememorytocachemostrecentlyusedandmostfrequentlyuseddata.Overthelastdecadeofusageinawiderangeofworkloads,ARChasprovenitseffectivenessanditsabilitytoout-performlegacyLeastRecentlyUsed(LRU)cachingimplementations.
• LessfrequentlyaccesseddataisstoredonSSDbasedL2ARCdevices.NexentaStorreferstotheL2ARCsimplyascache.Whencreatingastoragepool,youcandesignatedevicestobeusedasthecache.
• TheZFSintentlog(ZIL)accumulateswriteoperationsbeforefullwritetransactiongroupsareissuedtothebackendpooldevices.Tomaximizeperformanceofsmallsynchronouswriteoperations,hybridpoolsareconfiguredwithhighperformance,lowlatencySSDbasedsecondarylogdevices(SLOG)thatallowtheNexentaStornodetopro-activelyacknowledgewriteoperationstoclientapplications.
• InNexentaStor5,alldataiscompressedbeforebeingstoredonbackendmedia.ThedefaultalgorithmisLZ4,recommendedbecauseofitsperformanceandcompressionefficiencies.ARCoperatesoncompresseddata,furtheroptimizingitsuseofsystemDRAM.InNexentaStorHAclusters,SSDbasedlevel2ARCarealsopersistent,allowingcacheddatatobeimmediatelyavailabletoaNexentaStornodefollowingapoolfailover.
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Oneimportantparameterwhentuningpoolsforperformanceinvolvesconfiguringthepoolanddatasetrecordsize.InNexentaStor5,thedefaultrecordsizeforfilesystemsis128KB.Forvolumes,itis32KBbasedonthefactthatFCandiSCSILUNsaremoregenerallyusedforapplicationsandworkloadsthatgeneratesmall(er),randomIOs.Forstreamingtypeworkloadssuchaslargebackupandarchiveorlargevideostreamingsystems,NexentaStor5supportslargerrecordsizes,allthewayto1MB.
NexentaStor5supportsbothinlinecompressionandinlinededuplication.Inlinecompressionisenabledbydefaultonallstoragepoolswiththehigh-performanceLZ4algorithmbydefault.Inlinededuplicationcanbeusedbutisgenerallyrecommendedforlowercapacityappliances.NexentaStor5continuallymonitorsthesizeofthededuplicationtableandautomaticallyturnsoffdeduplicationifitdetectsariskofthededuplicationtablespillingoutoffastDRAMontoslowerpoolstorage,therebyprotectingthesystemfromunexpectedperformancedegradations.
Tofurtherfacilitatestoragepoolconfiguration,NexentaStor5includesprofilescontainingsettingstunedespeciallyforagivenstoragetype:All-FlashandGeneric.Forexample,ifyourNexentaStorappliancehasallSSDstoragedevices,youcanapplytheAll-Flashprofile,whichoptimizesperformanceforthiskindofconfiguration.AllstoragepoolsyousubsequentlycreateontheNexentaStorappliancewillautomaticallyhavetheprofilesettingsappliedtothem.
Forall-SSDconfigurations,NexentaStor5supportsautomatedorscheduledTRIM/UNMAPonthebackendSSDs.ForsomeSSDs,thiscanhelpmaintainperformance,lowerI/Olatency,andincreasetheusefullifeoftheSSDsinthepool.ThisfeaturecanalsobeusedforpoolsconfiguredontopofthinLUNspresentedbyabackendstoragearraythatsupportsUNMAPoperationstoreclaimunusedcapacityinthebackendarray.
3.3 DeviceFailureHandlingAsmentionedabove,besidesperformance,theothermainobjectiveofstoragepoolconfigurationisdurabilityandprotectingdataanddataservicesfromdevicefailures.NexentaStorsupportsraid0striped,mirror,single-parity,dual-parityandeventripleparitypoolconfigurations.
Asoflate2017,NexentaStor5referencearchitecturessupportNL-SASHDDsrangingfrom2TBallthewayto12TB.Poolsof2TBHDDsaregenerallyconfiguredwithmirrorvdevs,whilepoolswithdiskslargerthan4TBgenerallygetconfiguredwithdual-parity(4+2),(6+2)orlargervdevs.Animportantconsiderationinthevdevconfigurationiswhetherthesystemshouldberesilienttolossofafullstorageenclosure.Forexample,aphysicalsetupwith3separatestorageenclosurescansupporta(4+2)poolwithenclosurelevelredundancy(nomorethan2disksperenclosureforagivenvdev).
NexentaStorsupportstheallocationofanynumberofhotsparedevicestoapool.BothSSDsandHDDscanbeconfiguredashotsparesinahybridpool.Intheeventofadevicefailureinapool,NexentaStor5willautomaticallyactivatethe‘best’hotspare:aspareofthesametype(SSDorHDD),ofthesamesizeandpreferentiallyinthesamestorageenclosureasthefaileddevice.
NexentaledtheworkinOpenZFSonresilverperformance,enablingdeviceresilver(akadevicerebuilds)operationstogoasfastasthedevicecanhandlesequentialIOs.ThisNexentaStor5enhancementisparticularlycriticalforpoolswithlargeHDDstoreducedataexposuretofaileddevices.
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3.4 DataatRestEncryptionNexentaStor5supportsdataatrestencryptionforpoolsbuiltwithTCGEnterpriseSelf-EncryptingDrives.Thesolutionistransparenttoallotherfeaturesanddoesnothaveanyimpactonoverallsystemperformance.Fordataatrestencryptiontobeenabledonaparticularpool,alldevicesinitmustbeSEDcompliant,includingtheSSDsusedasSLOGorL2ARCdevicesinhybridpools.
Figure3-2:DataatRestEncryptionOverview
ThesolutionreliesonanexternalKMIPcompliantkeymanagementinfrastructure(e.g.KeySecurefromGemalto)toprovidethekeysrequiredtoaccessdataonthepooldevices.
3.5 FileSystemsandSharedFileServicesANexentaStorfilesystemisadatasetconfiguredinastoragepooltoprovidePOSIXcompliantstorageoffilesanddirectories.NexentaStorbenefitsfromOpenZFS’advanceddataintegrity,functionality,andscalability.Asaresult,NexentaStorsupportsfilesystemsofvirtuallyunlimitedsizes(effectivelyonlylimitedbythephysicalsizeofapool),easilyscalingtohundredsofterabytesandevenpetabytes.
Bydefault,filesystemsshareallthecapacityintheunderlyingpoolformaximumflexibility.ClientsaccessthefilesanddirectoriesusingstandardSMBandNFSprotocols.MicrosoftWindowsclientscommonlyuseSMBtoaccessfilesystemdata,whileclientsusingUNIXandUNIX-likeoperatingsystemscommonlyuseNFS.
ANexentaStorfilesystemhasanumberofpropertiesassociatedwithit.Thesepropertiescontrolsuchthingsasinlinecompressionsettings,defaultblocksizeforfilesinthefilesystem,users,groups,accesscontrollists,quotas,reservations,ICAPvirusscanning,andsoon.UsingtheNexentaStorAPIandCLI,youcansetthesepropertieswhenyoucreatethefilesystem,oryoucanmodifythemasneeded.
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Youcanconfiguremultiplefilesystemswithinastoragepool,andafilesystemcanhaveadditionalfilesystemsnestedbelowit(upto16levelsdeep).Bydefault,nestedfilesystemsinheritthepropertiesoftheirparent.Nestedfilesystemscanalsobecombinedwithdataprotectionservicessuchassnapshotandreplicationschedulestomaintainwriteconsistencyacrossthefullhierarchywheneversnapshotsaretakenontheparentfilesystem.
3.5.1 SharedFileServicesToallowWindowsclientsaccesstodatainaNexentaStorstoragepoolusingtheSMBprotocol,youcancreateafilesystemandconfigureSMB-relatedsettingsforthefilesystem,suchasaworkgrouptojoin,ActiveDirectorydomain,sharenames,etc.NexentaStor5providesSMBservicesthroughaNexentadevelopedkernelbasedSMBserverforbetterperformanceandscalability.
NexentaStor5shipswithSMB2.1asthedefaultSMBprotocolversionandaddssupportforSMB3toprovideahigh-performance,file-basedstoragebackendforMicrosoftHyper-Venvironments,includingOffloadedDataTransfer(ODX)toaccelerateHyper-VcopyoperationsoverSMB3.
ToallowclientsrunningUNIXandUNIX-likeoperatingsystemstoaccessstoragepooldatausingtheNFSprotocol,youcanconfigureNFSpropertiesforafilesystem.NexentaStor5supportsNFSv3(default)andNFSv4throughamature,highperformancekernelbasedNFSserver.
3.5.2 AccessControlListsNexentaStorimplementsNFSv4-styleACLsonitsfilesystems.Afilesystem’sACLconsistsofoneormoreAccessControlEntries(ACEs)thatspecifywhichusersandgroupsareallowedtoread,write,andmodifyfilesanddirectoriesinthefilesystem.YoucancreateandmodifyindividualACEsusingtheNexentaStorCLIandAPI.
NexentaStorACLsarecompatiblewithbothNFSandSMB,sothattheACLyoucreateforafilesystemappliestoclientsusingeitherprotocol.Thisprovidesthefoundationforfull-featured,concurrentSMBandNFSsharingofNexentaStorfilesystemsusingMicrosoftIDMapping.
3.5.3 Quotas,ReservationsandCapacityManagementAcriticalimplicationoftheNexentaStorpoolingmodelisthatallfilesystemspotentiallyhaveaccesstoallavailablecapacityinthepool.Thisisapowerfulfeaturethatcangreatlysimplifycapacitymanagementinalargesystem:ratherthanmanagingcapacityateachindividualfilesystemlevel,thestorageadministratorcansimplymonitoravailablecapacityattheaggregatepoollevel.
AnimportantOpenZFSbestpracticeistokeeputilizationofstoragepoolsbelow80%.Asacopyonwrite/redirectonwritefilesystem,OpenZFSneedsacertainamountofheadroomtoeffectivelymanageavailablespaceinastoragepool.Pushingutilizationabove85%willgenerallytranslateindegradedperformanceandhigherlatencies,particularlyonall-diskandhybridpools.
Tocontrolhowmuchcapacityaparticularfilesystem,aparticularuseroraparticulargroupcanconsume,NexentaStorsupportsconfiguringquotasandreservations.Areservationpro-activelycarvesoutcapacityfromthepoolandkeepsitasideforthesaidfilesystem.Aquotaontheotherhanddefinesthemaximumamountofcapacitythataparticularuserorgroupisallowedtoconsume.
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3.5.4 StorageQoSForFileServicesNexentaStorall-flashconfigurationsservingouthighperformance,lowlatency,NFSdatastorestoVMwarevSphereprivatecloudsisaverypopularusecase.ItispopularbecauseusersgetthemanagementsimplicityofNFSVMwaredatastores,withtheperformanceandeaseofuseofall-flash,andthecostsavingsofrunningsoftware-definedstorageonindustrystandardserversandSSDs.Forhostingprovidersrunninglarge-scalemulti-tenantvirtualizedinfrastructure,all-flashstoragealsohasthebenefitofsimplifyingday-to-dayoperationsandpracticallyeliminatingstoragerelatedcustomerescalations.
Insomeinstanceshowever,thereisaneedtocontrolstorageperformanceforsometenants;eithertoensurefairsharingofthebackendstorageresourcesbetweentenants,orensurethattenantsgetaccesstotheresourcestheyareentitledto,andnotmuchmore.Fortheseenvironments,NexentaStor5supportsQualityofServiceforfileservices.
Figure3-2:ExampleUseCaseforNexentaStorStorageQoS
Intheexampleabove,NexentaStorQoSisusedtodeliverdifferentiatedstorageperformancebetweenacoupleoftenants.TenantAhasaccesstoNFSdatastoreDS1whileTenantBhasaccesstoNFSdatastoreDS2.OnNexentaStor,DS1isconfiguredtoprovideupto300MB/sofbandwidthwhileDS2isconfiguredtoprovidenomorethan100MB/sofbandwidth.
ConfiguringQoSontheNexentaStorNFSshareallowsthehostingprovidertoeffectivelycaptheaggregatestorageresourcesconsumedbyaparticulartenantwhileleavingconfigurationofVirtualMachinelevelQoS(betterenforcedbythehypervisor)uptothetenantitself.
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3.6 VolumesandSharedBlockServicesSimilartohowfilesystemsaresupportedonstoragepools,NexentaStorsupportsthecreationofrawblockvolumesonstoragepools,tobesharedaseitheriSCSIorFibreChannelLUNs.Aswithfilesystems,youcanusetheNexentaStorCLItoconfigurepropertiesforvolumessuchasblocksize,compressionmode,andwhetherthevolumeisread-only.AllvolumesconfiguredonaNexentaStorpoolarethinbydefault.Configuringareservationonavolumewilleffectivelymakeitthick.
3.6.1 VolumeGroupsNexentaStor5requiresthatallvolumesbecontainedwithinapredefinedvolumegroup.Volumegroupssimplifytheprocessofconfiguringvolumesbyallowingyoutosetpropertiesonceatthevolumegrouplevelandrelyonpropertyinheritancefortheunderlyingvolumesinthegroup.
Forexample,tochangethecompressionpropertyforthevolumesinavolumegroup,youcouldsimplychangethevolumegroupcompressionpropertyratherthaneachvolume’scompressionproperty.Whenyousetthepropertyforthevolumegroup,allunderlyingvolumesinthegroupautomaticallyinheritit.
Volumegroupsalsoprovidethecriticalfunctionofconsistencygroupsfordataprotectionservices,providinganaturalcontrolpointfortransactionlevelconsistentsnapshotsacrossallunderlyingvolumes.Forexample,NexentaStorcanbeconfiguredtotakerecursivesnapshotsofallvolumesinavolumegroupaccordingtoaschedule.Thesnapshotscanbeclonedorrolledbackfortheentirevolumegroupatonce.
3.6.2 iSCSIBlockServicesNexentaStorvolumescanbesharedasiSCSILUNs.Todothis,youfirstcreateoneormoreiSCSItargetswithinNexentaStor,specifyingtheirassociatednetworkportal(s).NexentarecommendscreatingoneiSCSItargetperIPinterfaceintendedtosupportiSCSItraffic.
YouthenaddtheiSCSItargetsyoucreatedtoaniSCSItargetgroup.AniSCSItargetgroupisagroupofoneormoreiSCSItargetsthatwillprovideaccesstoasetofvolumes.NexentaStoralsoallowsyoutoconfigureiSCSIhostgroups,whicharegroupsofoneormoreiSCSIinitiators.
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Finally,youspecifyoneormoremappingsbetweenthevolumeandtheiSCSItargetgroupandiSCSIhostgroupsandLUNidentifier.TheinitiatorsintheiSCSIhostgroupthenhaveaccesstothevolumeusingtheLUNidentifieronthespecifiediSCSItargetgroup.TherelationshipbetweeniSCSItargets,iSCSItargetgroup,hostinitiatorgroupsandmappingsisshownbelow:
Figure3-3:TypicalNexentaStoriSCSIConfiguration
InaNexentaStorHAcluster,iSCSItargetsshouldbecreatedonVirtualIPaddressessothattheiSCSItargetsandiSCSItargetgroupsthatcontainthemcanseamlesslyfailoverbetweennodes,withthebackendstoragepoolcontainingthevolumestheyaresharing.
3.6.3 FibreChannelBlockServicesNexentaStor5supportsimplicitALUAconfigurationswhensharingFCLUNs.InordertosharevolumesasFCLUNs,yourlicensemustincludetheoptionalFibreChannelTargetfeature.ThisallowsyoutocreateFibreChanneltargetgroupsthatcontainFCtargetsfrombothnodesofaNexentaStorHAcluster.
SimilartohowlogicalmappingsaremanagedwithiSCSI,creatingFibreChannelhostgroupsandFCLUNmappingsthatcombineaFCtargetgroupwithaspecificFChostgroupandvolumeprovidegranularcontrolofLUNvisibilityacrosstheFibreChannelfabric.
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4 NexentaStorDataProtection
4.1 InstantSpaceOptimizedSnapshotsandClonesNexentaStorsupportsvirtuallyunlimitednumbersofhigh-performance,space-efficient,instantsnapshotsandclones.Itispossibletotakeindividualsnapshotsoffilesystemsandvolumestogetcrash-consistent,point-in-timecopiesoftheircontent.
Recursivesnapshotscanalsobetakenonnestedfilesystemsorvolumegroupstogettransaction-consistent,point-in-timecopiesofalltheirunderlyingchildrenfilesystemsorvolumes,respectively.
Figure4-1: NexentaStorHierarchicalDataConsistency
Asnapshotisaread-onlyrepresentationofadataset(thatis,afilesystem,volumegroup,orvolume)ataspecificpointintime.Snapshotsdonotconsistoftheactualdata,butpointerstowherethedataislocatedintheunderlyingpool.Becausetheydonotcontaindata,snapshotsaremuchsmallerinsizethanthedatatheyreference,allowingNexentaStortocollectandmaintainapracticallyunlimitednumberofsnapshots.
Snapshotscanbecloned.Whenyoucloneasnapshot,itcreatesanewdatasetthatisinitiallypopulatedwiththecontentsofthesnapshot.Unlikesnapshots,clonesarewritable,sothatyoucanadddatatothemasnecessary.
Acloneislinkedtotheoriginalsnapshotsothattheoriginalsnapshotcannotbedeletedwhileanyclonesofitexist.Aclonecanbepromoted,whichmakesitindependentofitsoriginalsnapshot.
UsingtheNexentaStorsnapshotrollbackfeature,youcanrestoreadatasettothestateitexistedinanyofthesnapshotsretainedontheappliance,assuringthatallversionsofthedatacapturedbysnapshotsareprotected.
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4.2 SnapshotServicesSnapshotsofadatasetcanbecreatedasneededusingtheCLIorRESTAPItools.NexentaStor5alsosupportsadvancedscheduledsnapshotservices(alsocalledsnappingjobs),whichcollectsnapshotsonarecurringbasisandspecifyhowmanysnapshotstomaintainperschedule.Scheduledsnapshotservicesareconfiguredtotakesnapshotsaccordingtoapredefinedschedule,fromeveryminutetoeveryhour,day,weekorevenmonth.
Snapshotservicesprovidegreatscaleandflexibility.Agivendatasetcanbeconfiguredwithmultiplesnapshotschedules,eachwithitsownretentionpolicyspecifiedintermsofnumberofsnapshotstokeep.Forexample,arecursiveservicecouldbeconfiguredonavolumegroupwith3schedules:“every2hours,keep12”,“everyday,keep7”and“everySaturday,keep52”.Thiswouldresultinayear’sworthofdataretention,with52weeklysnapshots,dailysnapshotsforthepastweekandbi-hourlysnapshotsforthepast24hours.
4.3 HighPerformanceReplicationOverviewNexentaStor5HighPerformanceReplication(HPR)providesfullfeatured,highperformanceremotereplicationfordisasterrecoveryoveranydistance.TheNexentaStor5replicationenginehasbeenmovedtotheoperatingsystemkernelformaximumperformanceandfine-grainedcontrolofRecoveryPointObjectives.Theresultisasolutionthatsupportedtwotypesofreplicationservices:
• ScheduledReplication(SR)–thisissnapshotbasedscheduledreplicationthat,withtherightlicenseoption,canbeusedforRecoveryPointObjectives(RPO)aslowas1minute.
• ContinuousReplication(CR)–thisiscontinuousasynchronousreplicationthat,withtherightlicenseoption,candeliverclosetozeroRPOoveranydistancewithoutaffectingapplicationperformanceontheprimarysite.CRworksbyasynchronouslyreplicatingeverywritetransactiongrouponthesourcedataset.
Asshownintheexamplebelow,HPRservicescanbeconfiguredbetweenfilesystems,volumesorvolumegroupsandaremanagedatthedatasetlevel,allowingbi-directionalreplicationbetweensites,albeitbetweendifferentsourceanddestinationdatasets.
Figure4-2:High-PerformanceReplicationExample
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HPRservicescaneitherbeconfiguredonaparticularfilesystemorvolume,ortheycanbesettorunrecursivelyonaparentfilesystemandallitsnestedchildrenfilesystems,oronavolumegroupandallthevolumesitcontains.Thisguaranteeswritetransactionlevelconsistencyacrossthesetofnesteddatasetsandcanbeusedtoimplementapplicationlevelconsistencygroups.
Figure4-3:ApplicationLevelConsistencyGroupsandHPR
NexentaStorHighPerformanceReplicationservicescanbeconfigured:
• Tomovedatasetsbetween2poolsonthesameNexentaStorappliance• ToreplicatedatasetsbetweenNexentaStorHAclusters• ToreplicatedatasetsbetweenamixofNexentaStorHAclustersandsinglenodeappliance
4.4 LicensingConsiderationsforHPRHighPerformanceReplicationissupportedbetweensystemsrunningNexentaStorversion5andabovewithEnterpriseEditionlicenses.
AsystemwiththebaseEnterpriseEditionlicensewillsupportScheduledReplicationservicesdeliveringRPOaslowas15minutes.
AsystemwiththeEnterpriseEditionlicenseandtheadditionalcontinuousreplicationoptionprovidessupportforScheduledReplicationwithRPOaslow1minute,aswellasContinuousReplicationservicesfornearzeroRPOoveranydistance.
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4.5 ScheduledReplicationServicesNexentaFusionandtheNexentaStorVMwarevCenterpluginprovidesimpleconfigurationandmanagementofHPRservices.MoreadvancedconfigurationoptionsareavailableusingtheNexentaStorCLIandRESTAPI.
BeforeconfiguringHPRservices,youmustensurethatallNexentaStorappliancessharethesameReplicationpassword.Thissharedpasswordistypicallysetatsoftwareinstallationtime.ItcanalsoberesetatanytimeusingtheNexentaStorCLI.ThesharedReplicationpasswordprovidesasimplecontrolmechanismtoprotectNexentaStorappliancesfromunauthorizeddatatransfers.
Ascheduledreplication(SR)serviceisdefinedbythePrimary(typicallysource)andSecondary(typicallydestination)datasetsandasetofoneormoreschedules.WhenascheduleiscreatedaspartofaSRservice,theuserspecifieshowmanysnapshotsforthatschedulemustbekeptonthePrimaryandontheSecondarysite.Itisimportanttonotethattheretentionpolicyissite-specificanddoesnotchangedependingonthedirectionofthereplicationstreams.
Figure4-4:ScheduledReplicationServicewithSiteSpecificRetentionPolicies
ByallowingmultipleschedulestobeconfiguredaspartofaSRservice,itispossible,forexample,toconfigureaservicewithanhourlyschedulethatkeeps12snapshotsonPrimaryand24onSecondary,andadailyschedulethatkeeps7snapshotsonPrimaryand30onSecondary.
NexentaStorSRservicesonlyreplicatethesnapshotsthatarecreatedaspartoftheservice.Snapshotscreatedonthesourcedataset(bylocalsnappingjobsforexample)arenotreplicatedbyHPR.
AspartofaSRservice,itispossibletocreateanon-demandsnapshotandhaveitimmediatelyreplicatedtothedestinationdataset.Schedule-specificretentionpoliciesdonotapplytotheseon-demandsnapshots,andtheymustbemanaged(i.e.eventuallyremoved)bytheenduser.
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WhileaSRserviceisactive,theusermaycreateacloneoutofanyofthesnapshotsonthedestinationdataset.Suchclonescanbeusedfordisasterrecoverytesting,forexample:
Figure4-5:ScheduledReplicationServicewithnon-disruptiveDRTest
Whileacloneexists,itsparentsnapshotisprotectedandwillbekeptonthedestinationdataset,independentoftheconfiguredretentionpolicy.Oncethecloneisdeleted,itsparentsnapshotisautomaticallyreturnedtotheSRserviceandwillbekeptordeletedaccordingtotheretentionpolicyoftheschedulethatoriginallycreatedthesnapshot.
ItisalsopossibletosharethedestinationfilesystemofanactiveHPRserviceas‘read-only’,allowingnon-disruptiveaccesstoitsdataforbackupandrestoreusecases.
HPRisarobustsolutionthatcanrecoverfromwidevarietyofunexpecteddisruptions,includingfullsiteoutages,aslongastherearecommonsnapshotsbetweenthePrimaryandSecondarysites.TheNexentaStorhprrecoverCLIcommandprovidesasimplesolutiontoautomaticallyrestartareplicationservicethatisinterruptedbychangesmadetothesourceordestinationdatasets.
AnotherimportantreliabilityfeatureofHPRistheabilitytoautomaticallyresumefrominterruptionsoflongrunningsnapshottransfers(forexample,duringtheinitialsynchronizationoperation):HPRisabletoautomaticallyrestartfromwhereitleftoffoncenetworkconnectivityisrestoredwithouthavingtoretransmitpreviouslytransferreddata.
4.6 ContinuousReplicationServicesContinuousReplicationservicescanbeconfiguredonfilesystems,volumesandvolumegroups.Therearenoschedules,retentionpolicies,orvisiblesnapshotstomanagewithCRservices,makingthemseeminglymuchsimplertooperatethanScheduledReplicationservices.
ItispossibletoconcurrentlyconfigurebothaCRandaSRserviceonthesamesourcedataset,replicatingto2differentdestinationdatasets,possiblyonthesameNexentaStorsystem.Insuchaconfiguration,theCRserviceprovidesnearzeroRPOprotectionfordisasterrecoverywhiletheSRservicecanbeusedformoretraditionalbackupandrestoreusecases.
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4.7 Multi-DestinationNexentaStorHPRsupportsmulti-destinationconfigurationsbyallowingmultipleSRservicestobeconfiguredonthesameprimarydataset.HPRdoesnotsupportcascadedreplication,however,sothestateofthevariousSRservicesthatshareacommonprimarydatasetmustbeconsistentwiththatlimitation.
Oneandonlyonecontinuousreplication(CR)serviceisallowedonaprimarydataset.However,HPRsupportshavingoneCRandoneormoreSRservicesconfiguredonthatprimarydataset,enablingconfigurationswhere,forexample,datasetAiscontinuouslyreplicatedtositeB,andreplicatedeverydaytositeCviaaseparateSRservice.
Figure4-6:HPRMulti-DestinationConfigurations
4.8 MovingDatasetToandFrom3rdPartyOpenZFSSystemsIndependentofHPR,NexentaStor5alsosupportstransfersofsnapshotsusingstandardOpenZFSsend&receiveoversshtoandfromsystemrunningstandardOpenZFSonLinux,FreeBSDorillumos.
Figure4-7:SnapshotTransferUsingStandardOpenZFSsend&receive
ContrarytoHPR,thisfeaturecanonlybeusedforon-demandsnapshottransferanddoesnotsupportschedules,orautomaticretentionpolicies.
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