Raid faq

Logical disk
RAID 0 disk array
Data stripe
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FAQ | RAID
RAID capabilities on HP Workstation platforms
What is RAID?
Redundantarrayofindependentdisks(RAID)providesamethodofcombiningmultipledisksintoasinglelogicalvolume
toincreaseperformanceorcreatedataredundancy.TherearemanyformsofRAID,seethedierencessectionformore
detailsonspecicRAIDcongurations.
What are the benets of RAID?
ThebenetsofRAIDvarybasedonthetypeofRAIDimplementedbutcanincludesomecombinationofthefollowing:
• Improvedperformance
• Dataredundancy
• Improvedresiliency(avoidingdowntime)
• Largerstoragevolumes
What terminology do I need to know?
Controller SpanningistheabilitytosupportRAIDcongurationsacrossmultiplecontrollers,includingAHCIand
NVMecontrollers.ControllerSpanningcanconsistofRAIDarraysconguredfromSATAorSASdevicesondisparate
controllers.NewerPCIestoragedevicesthathavestoragecontrollersbuiltintothedeviceonlysupportRAID
congurationsthatspanmultiplecontrollers.
Data redundancyistheexistenceofadditionaldatabeyondtheoriginaldatawrittenthatallowsfortherecoveryofdata
intheeventoferrorsorlossoforiginaldata.Theamountofdataredundancyandtheabilitytocorrectforerrorsvaries
based on the type of RAID array.
Parityisonemechanismtoprovidedataredundancyandallowsfortherecoveryofdataifadrivefails.Generationofthe
paritydatacantaketimeandismostecientwhendoneinhardware.
Hot sparesaresupportedonsomestoragecontrollers.Ifahotspareissupported,thedesignateddriveswill
automaticallyreplaceafaileddiskinamirror.Thehotsparemustbethesamecapacityorgreaterthanthelargestdiskin
thearray.Twohotsparescanbedesignatedforonearray,ortwodierentarrayscaneachbedesignatedonehotspare.
What RAID congurations are available?
RAID 0–Createsasinglevolumethathasdatastripedacrosstwoormoredrives.Thesedrivesaretypicallyonone
controllerunlessControllerSpanningissupported.Thesizeofthevolumeisbasedonthesizeofthesmallestcapacity
drivetimesthenumberofdrivesintheRAID0conguration.RAID0isusedtoeitherimproveperformancesincedatacan
besenttomultipledrivesinparallelortocreatealargervolumeaseachdriveinthevolumeaddsadditionalcapacity.
ThereisnodataredundancyorparityinaRAID0conguration.IfanyharddrivememberinaRAID0congurationfails,
alldataislostfortheentirearray.ThemainadvantageofRAID0isperformanceandanincreasedvolumesize.