SAS(SerialAttachedSCSI)istheserialstorageinterfacethathasbeendesignedtoreplaceandupgradeSCSI,byfarthemostpopularstorageinterfaceforhigh-performancesystemsformanyyears.RetainingbackwardcompatibilitywiththemillionsoflinesofcodewrittentosupportSCSIdevices,SASincorporatesrecentadvancesinhigh-speedserialdesigntoprovidebetterperformance,betterreliabilityandenhancedcapabilities,allatalowercost.SASwillbeasignificantpartofmanyfuturehigh-performancestoragesystems,andhardwaredesigners,systemvalidationengineers,devicedriverdevelopersandothersworkinginthisareawillneedaworkingknowledgeofit.SASStorageArchitectureprovidesacomprehensiveguidetotheSASstandard.Thebookcontainsdescriptionsandnumerousexamplesoftheconceptspresented,usingthesamebuildingblockapproachasotherMindShareofferings.Thisbookdetailsimportantconceptsrelatingtothedesignandimplementationofstoragenetworks.Specifictopicsofinterestinclude:SATACompatibilityExpanderdevicesDiscoveryProcessConnectionprotocolsArbitrationofcompetingconnectionrequestsFlowControlprotocolsACK/NAKprotocolPrimitivesconstructionandusesFramesformat,definition,usedofeachfieldErrorcheckingmechanismsDescriptionofresponsibilitiesforeachlayer:ApplicationlayermodeandlogpagesTransportLayerframeconstructionPortLayercallcentermodelLinkLayerestablishandmaintainconnectionsPhyLayerOOB,Initialization,andResetPhysicalLayerconnectorsandcablesSerialSupportserialtransmissionsupportrequirementsThefutureofSAScompetitionwithSATAandFibreChannelintheservermarketplace
1