SANconfigurations thatcontainSANVolumeControllerclusterscanbesetup invarious ways.
“Maximumconfiguration”onpage64
Ensurethatyouarefamiliarwiththemaximumconfigurationsof theSAN VolumeController.
Configuration rules
SANconfigurationsthatcontain SANVolumeControllerclusterscanbesetupin various ways.
Someconfigurations donotworkandareknownasinvalid.Youcanavoidcreating invalid configurationsifyou followtherulesthataregiveninthissection.
ASANconfigurationthatcontainsSANVolumeControllers isvalidif itobservesall of thefollowingrules.Theserulesarediscussedinthefollowingsection.
Relatedconcepts
“Storagesubsystems”
Followtheseruleswhenplanningtheconfigurationofstoragesubsystemsinthe SANfabric.
Relatedreference
“Hostbus adapters”onpage 55
Followtheseconfigurationrules forhostbusadapters (HBAs).
“Nodes”onpage56
Followtheseconfigurationrules fornodes.
“Powerrequirements”onpage57
Notethepowerrequirementsfor theSANVolumeController.
“Fibre-channelswitches” onpage57
Followtheseguidelinesforconfiguring thefibre-channelswitchesthatare supportedontheSAN.
Storage subsystems
Follow theserules whenplanningtheconfigurationof storagesubsystemsinthe SANfabric.
AllSANVolumeControllernodesof aclustermust beableto seethesamesetof storagesubsystemportsoneachdevice.Anyoperation thatisinthismode in which twonodesdonotseethesamesetofportsonthesamedeviceisdegraded, andthesystem logserrorsthatrequestarepairaction.Thisrulecan have
important effectsonstoragesubsystemsuchasFAStT,whichhasexclusion rules thatdeterminetowhich hostbusadapter(HBA)WWNNs astoragepartitioncanbe mapped.
AconfigurationinwhichaSANVolumeControllerbridgesaseparatehost device anda RAIDarrayisnotsupported.Typicalcompatibilitymatrixesareshownina documenttitledSupportedHardwareListonthefollowingWebpage:
http://www-1.ibm.com/servers/storage/support/virtual/2145.html
TheSANVolumeControllerclustersmust notshare itsstoragesubsystemdevices withhosts.Adevicecan besharedwithahostundercertainconditions as
describedinthistopic.
Two SANVolumeControllerclustersmustnotshare thesamestoragesubsystem.
Thatis,onedevice cannotpresentLUstotwo differentSANVolumeController clusters.Thisconfigurationisnotsupported.
TheSANVolumeControllermustbeconfiguredtomanageonly LUNsthatare presentedbysupporteddiskcontrollersystems.Operationwithotherdevicesisnot supported.
Unsupported storagesubsystem(genericdevice)
When astoragesubsystemisdetectedontheSAN,theSANVolumeController attempts torecognizeit usingitsInquirydata. Ifthedeviceisrecognizedasoneof theexplicitlysupportedstoragemodels, thentheSANVolumeControlleruseserror recovery programsthatarepotentiallytailoredtotheknownneedsof thestorage subsystem.Ifthedeviceisnotrecognized,thentheSANVolumeController configuresthedevice asa genericdevice.Agenericdevice mayormaynot function correctlywhenaddressedbyaSANVolumeController.Inany event,the SANVolumeControllerdoesnotregardaccessingagenericdevice asanerror conditionand,consequently, doesnotloganerror.MDiskspresentedbygeneric devicesarenoteligibleto beused asquorumdisks.
Split controllerconfigurations
If asingleRAIDcontrollerpresents multipleLUs,eitherbyhavingmultipleRAID arraysconfiguredorbypartitioningoneormoreRAIDarraysintomultipleLUs,then each LUcanbeownedbyeitherSANVolumeControlleroradirectattachedhost.
Suitable LUNmaskingmust beinplacetoensurethatLUsarenotsharedbetween SANVolumeControllersanddirectattachedhosts.
In asplitcontrollerconfiguration,aRAIDarraypresents LUsto bothaSANVolume Controller(which treatstheLUasanMDisk)andtoanotherhost.TheSANVolume Controllerpresents VDiskscreatedfromtheMDiskto anotherhost.Thereisno requirementfor thepathingdriverinthetwo hoststo bethesame(although,if the RAIDcontrollerwereanESS,bothhostswoulduseSDD).Figure17onpage 53 shows thattheRAIDcontrollerisaFAStT,withRDACusedfor pathingonthe directly attachedhost, andSDDused onthehostthatisattachedwiththeSAN VolumeController. HostscansimultaneouslyaccessLUs,thatareprovidedbythe SANVolumeControlleranddirectlybythedevice.
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In thecasewheretheRAIDcontrollerisanESS, thepathingdriver inthehost wouldbeIBMSubsystemDeviceDriver(SDD)fortheESSandSDDfortheSAN VolumeControllerLUs.Figure18onpage54showsasupportedconfiguration becausethesamepathingdriver isusedforboth directandvirtualdisks.
Host Host
SDD RDAC
VDisk
MDisk Array San Volume Controller
SAN
Disk array
Figure17.DiskcontrollersystemsharedbetweenSANVolumeControllerandahost
Figure19onpage 55illustratesanotherconfiguration.
Host
SDD
VDisk
MDisk Array San Volume Controller
SAN
ESS
Figure18.ESSLUsaccesseddirectlywithaSANVolumeController
Relatedreference
“Configurationrules”onpage51
SANconfigurations thatcontainSANVolumeControllerclusterscanbesetup invarious ways.