Specifications

Storage Subsystem Guide 7
System Overview
Public Data
Network
Thepublicdatanetwork,fromthestorageserverperspective,consistsofthe
publicEthernetportontheSMU,andmanagementaccesscanbeenabledon
individualGigabitEthernet(GE)interfacesonthestorageserver.
ClientsconnecttotheSMUthroughthepublicdatanetwork,andclient
connectionsaremadethroughthe
publicdatanetwork.Itisalsopossibleto
configurestorageservers/clusterssothattheycanbemanagedusingthe
publicdatanetwork.
Storage
Subsystem
Storagesubsystemscontainthedevicesthatstorethedatamanagedbythe
storageserver.Theserverallowsyoutosimultaneouslyconnectmultiple
diversestoragesubsystemsbehindasingleserver(orcluster),which
integratesallphysicalstorageresourcesintooneormorelogicalfilesystems.
Eachstoragesubsystemismadeupof
RAIDcontrollers,storagedevices,and
theFibreChannel(FC)infrastructure(suchasFCswitchesandcables)usedto
connectthesedevicestoasinglestorageserverorcluster.
Storage Subsystem Characteristics
ThestoragesubsystemsusehardwareRAIDcontrollers,whichprovide
completeRAIDfunctionalityandenhanceddiskfailuremanagement.The
numberofcontrollersinthesystemdependsonitsstoragecapacity.
Somestoragesubsystemsuseonlyonetypeofdisk(FC,SATA,orSAS).Some
storagesubsystemscanusedifferentdisktechnologies,and
mayevenbeable
tomixdisktypeswithinastoragesubsystem(butmixingdrivetypeswithina
storageenclosureisnotsupported).
Hot Spare Disk
Ahotsparediskisaphysicaldiskthatisconfiguredforautomaticuseinthe
eventthatanotherphysicaldiskfails.Shouldthishappen,thesystem
automaticallyswitchestothehotsparediskandrebuildsonitthedatathat
waslocatedonthefaileddisk.Thehotsparedisk
musthaveatleastasmuch
capacityastheotherdisksinthesystemdrive.Thehotsparediskisaglobal
hotspare,meaningthatonlyonehotsparediskisrequiredperRAIDrack,but
SGIrecommendshavingseveralhotsparesperracktomaintainahigher
margin
ofsafetyagainsthardwarefailures.