1Copyright2015EMCCorporation.
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RAIDShield:Characterizing,Monitoring,andProactivelyProtectingAgainstDiskFailuresPresenter:AoMaAjointworkwithFredDouglis,GuanlinLu,DarrenSawyerSurendarChandra,WindsorHsu2Copyright2015EMCCorporation.
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DiskfailuresarecommonplaceWhole-diskfailurePartialfailureRAIDiswidelydeployedProtectdataagainstfailureswithredundancyPervasiveRAIDProtection3Copyright2015EMCCorporation.
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StoragesystemisevolvingEscalateduseoflessreliabledrivescausesmorewhole-diskfailuresIncreasingdiskcapacityresultsinmoresectorerrorsSolutionAddextraredundancy(RAID5,RAID6,…)–EnsuredatareliabilityatthecostofstorageefficiencyRAIDOverviewIsaddingextraredundancyanefficientsolution4Copyright2015EMCCorporation.
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Analyzed1millionSATAdisksandrevealedFailuremodesdegradingRAIDreliabilityReallocatedsectorsreflectdiskreliabilitydeteriorationDiskfailureispredictableBuiltRAIDSHIELD,anactivedefensemechanismReconstructfailingdiskbeforeit'stoolate!
PLATE:single-diskproactiveprotection–Deploymenteliminates70%ofRAIDfailuresARMOR:diskgroupproactiveprotection–RecognizevulnerableRAIDgroupsWhatWeDid5Copyright2015EMCCorporation.
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BackgroundDiskfailureanalysisRAIDSHIELD:IdentifyfailureindicatorReallocatedSector(RS)characterizationSinglediskproactiveprotectionDiskgroupproactiveprotection5Outline6Copyright2015EMCCorporation.
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Diskfailuredoesnotfollowafail-stopmodelTheproductionsystemsstudieddefinefailureasConnectionislostAnoperationexceedsthetimeoutthresholdWritefailsWhole-diskFailureDefinition7Copyright2015EMCCorporation.
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EachdiskdrivemodelisdenotedasRelativesizeswithinafamilyareorderedbythecapacitynumber–E.
g.
A-2islargerthanA-1DiskModelPopulation(Thousands)FirstDeploymentLogLength(Months)A-13406/200860A-216511/200860B-110006/200848C-19310/201036C-225312/201036D-138409/201121DiskDataCollection8Copyright2015EMCCorporation.
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WhatDoRealDiskFailuresLookLike9Copyright2015EMCCorporation.
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0001424462031010203040500-612-1824-3036-4248-54A-2MonthDistributionofLifetimeofFailedDrives001241534291130102030400-612-1824-3036-4248-54A-1MonthAlargefractionoffaileddrivesarefoundatasimilaragePercentage(%)Percentage(%)10Copyright2015EMCCorporation.
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ThenumberofaffecteddiskskeepgrowingAbout10%ofdisksgetsectorerrorsatthe3rdyearSectorerrornumbersincreasescontinuouslyAverageerrorcountincreases25%to300%yearoveryearIncreasingFrequencyofSectorErrors11Copyright2015EMCCorporation.
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DrivefailingatasimilarageFailurerateisnotconstantAhighriskofmultiplesimultaneousfailuresIncreasingfrequencyofsectorerrorsExacerbateriskofreconstructionfailuresPassiveRedundancyisInefficientEnsuringreliabilityintheworstcaserequiresaddingconsiderableextraredundancy,makingitunattractivefromacostperspective12Copyright2015EMCCorporation.
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MotivationEnsuredatasafetywithminimalredundancyProactivelyrecognizeimpendingfailuresandmigratevulnerabledatainadvanceMethodologyIdentifyindicatorofimpendingfailureIndicatorcharacterizationProactiveprotectionRAIDSHIELD,TheProactiveProtection13Copyright2015EMCCorporation.
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PotentialindicatorsVariousdiskerrorsCriteriaofagoodindicatorIthappensmuchmorefrequentlyonfaileddisksratherthanworkingdisksApproachQuantifythediscriminationbetweenerrorvalueonfaileddisksandworkingones–DecilescomparisonisusedIdentifyFailureIndicator14Copyright2015EMCCorporation.
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FaileddiskshavemoremediaerrorsthanworkingonesThediscriminationisnotsignificantenoughMediaErrorComparison2359152232478611123471330020406080100123456789faileddiskworkingdiskDecilesA-2MediaErrorCount15Copyright2015EMCCorporation.
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2238718732752281212422025000001262905001000150020002500123456789faileddiskworkingdiskA-2DecilesReallocatedSectorCountA-2DecilesRSisstronglycorrelatedwithdiskfailuresReallocatedSector(RS)Comparison16Copyright2015EMCCorporation.
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MostfaileddrivestendtohavealargernumberofRSthanworkingonesRSisstronglycorrelatedwithwhole-diskfailures,followedbymediaerrors,pendingsectorerrorsanduncorrectablesectorerrorsCorrelationBetweenSectorErrorsAndWhole-diskFailureRSisastrongindicatorofimpendingdiskfailure17Copyright2015EMCCorporation.
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LargerRScountimplieshigherfailurerateintwo-monthwindowDiskFailureRateGivenDifferentRSCount1.
767758083858689909091929393949502040608010004080120160200240280320360400440480520560600DiskFailureRate(%)RScountA-2RSCharacterization(1)18Copyright2015EMCCorporation.
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LargerRScount,fastertofail10%25%median75%90%RSCountTimeMargin(Days)DiskFailureTimeGivenDifferentRSCountRSCharacterization(2)19Copyright2015EMCCorporation.
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RScountindicatesthedegreeofdiskreliabilitydeteriorationUsetheRScounttopredictimpendingdiskfailureinadvancePLATE:SingleDiskProactiveProtection20Copyright2015EMCCorporation.
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70.
166.
66461.
859.
952.
14742.
63936.
94.
52.
82.
11.
71.
40.
80.
70.
40.
30.
27010203040506070809010020406080100200300400500600failurespredictedfalsepositivePercentage(%)BoththepredictedfailureandfalsepositiveratesdecreaseasthethresholdincreasesSimulationResult:FailuresCapturedRateGivenDifferentRSThresholdRSthreshold21Copyright2015EMCCorporation.
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551515801070020406080100WithoutProactiveProtectionWithProactiveProtectionHardwareFailuresOthersTripleFailuresEliminatedTripleFailuresSingleproactiveprotectionreducesabout70%ofRAIDfailures,equivalentto88%ofthetriple-diskfailuresPLATEDeploymentResult:CausesofRecoveryIncidentsPercentage(%)22Copyright2015EMCCorporation.
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10%remainingtriplefailuresPLATEmissesRAIDfailurescausedbymultiplelessreliabledrives,whoseRScountshaven'texceedthethresholdTriagePrioritizediskgroupswithhighestriskMotivationofARMOR:TheRAIDGroupProactiveProtection23Copyright2015EMCCorporation.
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1-11-21-31-42-12-22-32-43-13-23-33-44-14-24-34-4XXXXThreatofFailureImminentFailureGoodDiskHealthyDG1ImminentFailureofDG2ProtectedDG3PossibleFailureofDG4Singlediskprotection:Replace2-3,2-4,3-4(PLATE)Can'tidentifyDG4northedifferencebetweenDG2andDG3Groupprotection:ReplaceDG4orincreaseredundancy(ARMOR)ProtectDG4andrecognizethedifferencebetweenDG2andDG3DiskGroupProtectionExample24Copyright2015EMCCorporation.
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CalculatethesinglediskfailureprobabilityConditionalprobabilitythroughBayesTheoremCalculatetheprobabilityofavulnerableRAIDCombinationofthosesinglediskprobabilitiesthroughjointprobabilityARMORMethodology25Copyright2015EMCCorporation.
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ThediscriminationshowsARMORiseffectivetorecognizeendangeredDGsInpractice,itidentifiesmostDGfailuresthatarenotpredictedbyPLATEProbabilityDecilesdistributionEvaluation0.
250.
330.
390.
440.
460.
50.
630.
730.
930.
150.
20.
230.
250.
270.
280.
30.
310.
3200.
20.
40.
60.
81123456789GroupswithmorethanonefailureGroupswithoutfailure26Copyright2015EMCCorporation.
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GooglereportsSMARTmetricssuchasreallocatedsectorstronglysuggestanimpendingfailure,buttheyalsodeterminethathalfofthefaileddisksshownosucherrors[Pinheiro'07]DifferentworkloadandRAIDrewriteDiskfailurepredictionAveragemaximumlatency[Goldszmidt'12]SMARTfailureprediction[Murray'05,Hughes'02]RelatedWork27Copyright2015EMCCorporation.
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Weanalyzed1millionSATAdrivesObservefailuremodesdegradingRAIDreliabilityRevealRScountreflectsthediskreliabilitydeteriorationDiskfailureispredictableWebuiltRAIDSHIELD,anactivedefensemechanismPLATE:singlediskproactiveprotection–Deploymenteliminates70%ofRAIDfailuresARMOR:diskgroupproactiveprotection–RecognizevulnerableRAIDgroups–HopetodeployinfutureIsaddingextraredundancyanefficientsolutionUseasmuchredundancyasneededtoensureavailabilityProactivereplacementshoulddecreasethelevelneededSummary28Copyright2015EMCCorporation.
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RAIDShield:Characterizing,Monitoring,andProactivelyProtectingAgainstDiskFailuresQuestionsAcknowledgementAndreaArpaci-DusseauandRemziArpaci-DusseauDataDomainengineerteam,membersofADandCTOoffice,StephenManley29Copyright2015EMCCorporation.
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CalculatethesinglediskfailureprobabilityCalculatetheprobabilityofavulnerableRAID
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PhotonVPS 服务商我们是不是已经很久没有见过?曾经也是相当的火爆的,我们中文习惯称作为饭桶VPS主机商。翻看之前的文章,在2015年之前也有较多商家的活动分享的,这几年由于服务商太多,乃至于有一些老牌的服务商都逐渐淡忘。这不有看到PhotonVPS商家发布促销活动。PhotonVPS 商家七月份推出首月半价Linux系统VPS主机,首月低至2.5美元,有洛杉矶、达拉斯、阿什本机房,除提供普...
2021年各大云服务商竞争尤为激烈,因为云服务商家的竞争我们可以选择更加便宜的VPS或云服务器,这样成本更低,选择空间更大。但是,如果我们是建站用途或者是稳定项目的,不要太过于追求便宜VPS或便宜云服务器,更需要追求稳定和服务。不同的商家有不同的特点,而且任何商家和线路不可能一直稳定,我们需要做的就是定期观察和数据定期备份。下面,请跟云服务器网(yuntue.com)小编来看一下2021年国内/国...
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