桌面级硬盘、近线级硬盘与企业级硬盘的区别

Desktop,Nearline&EnterpriseDiskDrivesWhat’sthedifference?WillisWhittington,SeagateTechnologyFeb21st,2008AbstractDesktop,Nearline&EnterpriseDiskDrivesWhat’sthedifference?Forthepasttwentyfiveyearsthestoragemarketplacehasbeendividedintotwomajorcategoriesnamely“Desktop”and“Enterprise”.Recently,athirdplayervariouslyknownas“Nearline”,“Reference”or“BusinessCritical”hasevolvedtoprovidealowcost,highcapacitystoragesolutionforEnterprisedatathatnolongerneedstoexistinahighavailabilitytransactionalprocessingenvironmentbutmustmaintain24x7availabilityasareferenceorbackupresource.Eachoftheseclassesofdrivesrequiresauniqueandspecificsetofattributestofulfillitsrole.Thispresentationwillexplorethesedifferencesandexplainwhyyouneedtousetherightdrivefortherightapplication.AgendaBasicComparisonsSAS&SATACompatibilityTheAdvantagesofNearlineSASRotationalVibrationDataErrorRateErrorCorrectionCapabilityDataIntegrityPerformanceAnnualizedFailureRate~Q&Aalongtheway~BasicComparisonsComparisonTableDT/NL/MC*MetricDesktop(DT)SATANearline(NL)SASNearline(NL)EnterpriseMC*Capacity(GB)1,0001,0001,000Mid1.2x+1,200,000Low/Medium(20%)EDC/ECC+ProprietaryDataIntegrityProtectionUnrecErrorRate10-1410-1510-1510-1612.5FullSCSISCSI+Adv.Features(EnabledbyDualCPU)8,760(LowDutycycle)16Hosts&DualPort1x+YesHigh+DualPort450CostLowMidHighPowerConsumption1x1.2x1.5xMTBF(Hrs)600,0001,200,0001,600,000DutyCycleLow(10%)Low/Medium(20%)High(100%)DataIntegrityParity(?)EDC+(ECC?)EDC/ECC+ProprietaryDataIntegrityProtectionFirmware/FeaturesStandardSATASATA+SelectedNearlineFeaturesSCSI+Adv.Features(EnabledbyDualCPU)PowerOnHrs/Year24008,760(LowDutycycle)8,760Performance1x1x1.4x/2.5x(Seq/Rand)T10DataProtectionNoNoYesMultiInitiatorNoNo16Hosts&DualPortScalabilityLowLowHigh+DualPortRVRadians/sec2612.521ErrorRecoverySATASATA+TimeControlFullSCSI*MissionCriticalKey:GoodBetterBest2xDuplex2xDuplexAnatomyofanEnterpriseDriveMotorHigherrpmthanNLorDTTighterspecificationsLessrunoutMoreexpensiveDiscsFourplatterdesignSmallerdiameterthanNL/DTFullmediacertificationFullycharacterizedVariablesectorformatAnatomyofanEnterpriseDriveHeadStackEightheaddesignLowmass,highrigidityVoicecoildesignedforooptimalperformanceo100%dutycycleHighercostdesignAnatomyofanEnterpriseDriveEnvironmentalControlModuleHumidityControlChemicalAbsorbtionMulti-pointfiltrationWindageDesignAnatomyofanEnterpriseDriveMiscMechanicalPowerfulVoiceCoilMotorStifferCoversAirControlDevicesFasterSeeksHighServoSampleRateLowRVsusceptibilityAnatomyofanEnterpriseDriveElectronicsDualprocessorsMultihostqueuingDualportTwicethememoryofNL/DTHighrpmcontrolCommandschedulingSuperiorerrorprotectionSuperiorerrorcorrectionSmartservoalgorithmsPerform.optimizationDataintegritychecksSequentialh/wassistAnatomyofanEnterpriseDriveConSAS&SATACompatibilityI/OConnectorsforSAS&SATARxTxDataGndGndVoltagePins3.3V5V12VKeyLED/Spin-upForSAS,thekey-wayisfilledinanditsflipsideisusedforthe2ndPortThispreventsaSASdrivefrombeingpluggedintoaSATAcabinetslot.EnclosureDriveVccVccEnclosure~3msecDriveVccVccCurrentLimitedSteadyStateConTheAdvantagesofNearlineSAS100%PhyCompatibleConcurrentDataChannelsFullDuplex(Bidirectional)I/OEnd-to-EndDataIntegrityVariableSectorSizeEnterpriseCommandQueuingFullSCSICommandSetMultipleHostSupportFullEDC&ECCDualPortNEARLINESATANEARLINESASSteppinguptoSASprovidesMissionCriticalCompatibilityNLSATAComparedtoNLSASSAS/SATANLPhysicalDifferencesSATAElectronicsSASPort“B”NearlineHead/DiscAssy.SASElectronicsSAS/SATANLDifferencesSATASASSASSATAXmitsInonedirectionatonetimeXmitsInbothdirectionsatonetimeDualPortOneDataChannel1Write1ReadORCHANNEL1CHANNEL2HalfDuplexFullDuplexTwoDataChannels2ConcurrentWrites2ConcurrentReads1Write+1ReadORORMultiHostCommandQueuingSASSASSASSATAEXPANDEREXPANDERInterposerInterposertohandleQ’ingfor2ndhostDriveQueueSupports16HostsDriveNCQ*supportsasingleHost*NativeCommandQueuingNLSAS/SATASummaryBothSATAandSASNearlinedrivesaredesignedforuseinEnterpriseMissionCriticalenvironments.SASNearlinedriveshaveadditionaladvantageswhicharemadepossiblebytheSerialSCSIinterfaceandenterpriseelectronics:•Fullsysteminterfacecompatibilityattheprotocol,physical(“phy”),andcommandlevel•Enterpriseerrorrecoveryandperformanceoptimizationcontrols•FulldataintegrityprotectionbothwithinthedriveandatthesystemlevelwithDIFsupport.RotationalVibration•PSdrivesarenotdesignedforbackplane(JBOD/SBOD)useandarenotequippedtocopewiththeeffectsofRVHDAsubjectedtorotationalforcesRVEmittedbyaSeekingDriveNeighboringDrive’sServoneedstocompensateforexternallyinducedRVCoilCurrentRVisProportionaltoSeekCurrent‘ScopePicture,SeagateProd.Dev.CurrentinVoiceCoilDiscMovementRotationalVibrationDesktopBarracudaESEnterprise-020406080100120612.521rads/sec20102030405060020406080100120%Degradation02030405060RVLevel(Rad/sec2)DesktopEnterpriseNearlineNearlineEnterpriseDesktopImpactonPerformance**Source:STXCompetitiveAnalysis.051015202530354045123456789101112131415161718192021222324252627282930313233CabinetTestedrads/sec2(rms)RVin33DifferentCabinetsRotationalVibrationMorestringentRVspec.neededforSATAcabinetsR