Tuning Networks.docx
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Tuning Networks.docx
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TuningNetworks
TuningNetworks
Thischapterdescribesdifferentconnectionmodelsandintroducesnetworkingissuesthataffecttuning.
Thischaptercontainsthefollowingsections:
∙UnderstandingConnectionModels
∙DetectingNetworkProblems
∙SolvingNetworkProblems
UnderstandingConnectionModels
Thetechniquesusedtodeterminethesourceofproblemsvarydependingontheconfiguration.Youcanhaveasharedserverconfigurationoradedicatedserverconfiguration.
∙Ifyouhaveasharedserverconfiguration,thenLSNRCTLserviceslistsdispatchers.
∙Ifyouhaveadedicatedserverconfiguration,thenLSNRCTLserviceslistsdedicatedservers.
Itispossibletoconnecttodedicatedserverwithadatabaseconfiguredforsharedserversbyplacingtheparameter(SERVER=DEDICATED)intheconnectdescriptor.
SharedServerConfiguration
Thissectiondiscussesthesetupsforthesharedserverconfiguration.
RegisteringtheDispatchers
TheLSNRCTLcontrolutility'sservicesstatementlistseverydispatcherregisteredwithit.ThislistincludesthedispatchersprocessID.Youcancheckthealertlogtoconfirmthatthedispatchershavebeenstartedsuccessfully.
Note:
RememberthatPMONcantakeaminutetoregisterthedispatcherwiththelistener.
LSNRCTL>services
Connectingto
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=helios)(PORT=1521)))
ServicesSummary...
Service""has1instance(s).
Instance"sales",statusREADY,has3handler(s)forthisservice...
Handler(s):
"DEDICATED"established:
0refused:
0state:
ready
LOCALSERVER
"D000"established:
0refused:
0current:
0max:
10000state:
ready
DISPATCHER helios,pid: 1689> (ADDRESS=(PROTOCOL=tcp)(HOST=helios)(PORT=52414)) "D001"established: 0refused: 0current: 0max: 10000state: ready DISPATCHER helios,pid: 1691> (ADDRESS=(PROTOCOL=tcp)(HOST=helios)(PORT=52415)) Thecommandcompletedsuccessfully. SeeAlso: OracleNetServicesAdministrator'sGuideforinformationonsettingtheoutputmode ConfiguringInitializationParametersforSharedServers Thefollowinglistprovidesinformationonconfiguringinitializationparametersforsharedservers. ∙MakesurethattheDISPATCHERSlineiscorrectlyset.Forexample: ∙DISPATCHERS="(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP) ∙(HOST=hostname)(PORT=1492)(queuesize=32))) ∙(DISPATCHERS=1) ∙(LISTENER=alias) ∙(SERVICE=servicename) ∙(SESSIONS=1000) ∙(CONNECTIONS=1000) ∙(MULTIPLEX=ON) ∙(POOL=ON) ∙(TICK=5)" ∙ One,andonlyone,ofthefollowingattributesisrequired: ∙PROTOCOL ∙ADDRESS ∙DESCRIPTION ADDRESSandDESCRIPTIONprovidesupportforthespecificationofadditionalnetworkattributesbeyondPROTOCOL.Inthepreviousexample,theentireDISPATCHERSlinecanbe(PROTOCOL=TCP).TheattributesDISPATCHERS,LISTENER,SERVICE,SESSIONS,CONNECTIONS,MULTIPLEX,POOL,andTICKSarealloptional. MakesurethattheoptionalMAX_DISPATCHERSlineiscorrectlyset.Forexample: MAX_DISPATCHERS=4 Thislineshouldreflectthetotalnumberofdispatchersyouwanttostart. MakesurethattheoptionalMAX_SHARED_SERVERSlineiscorrectlyset.Forexample: MAX_SHARED_SERVERS=5 ThislinesetstheupperboundonthetotalnumberofsharedserversPMONcancreate,basedonthepeakloadofthesystem.Thisshouldbesethighenoughsothatallrequestscanbeserviced,butnotsohighthatthesystemswapsiftheyarereached.Thepurposeofthisparameteristopreventtheserverfromswapping.Runthefollowingscripttoseewhatthehighwatermarkisforthenumberofserversrunning,andthensetMAX_SHARED_SERVERStomorethenthis. SELECTmaximum_connections"MAXCONN",servers_started"STARTED",servers_ terminated"TERMINATED",servers_highwater"HIGHWATER"FROMV$SHARED_SERVER_ MONITOR; ∙MakesurethattheoptionalSHARED_SERVERSlineiscorrectlyset.Forexample: ∙SHARED_SERVERS=5 ∙ Thisisthetotalnumberofsharedserversstartedwhenthedatabaseisstarted.ItalsorepresentsthetotalnumberofsharedserversPMONtriestokeep.Itshouldbethetotalnumberofserversexpectedtobeusedwhenthedatabaseisactive.MAX_SHARED_SERVERSisintendedtohandlepeakload. CheckingtheConnections UsetheLSNRCTLcontrolutility'sservicescommandtoseeifthereareexcessiveconnectionrefusals.Checkthelistener'slogfiletoseeifthisisaconnectionproblem.Forexample: LSNRCTL>services Connectingto (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=helios)(PORT=1521))) ServicesSummary... Service""has1instance(s). Instance"sales",statusREADY,has2handler(s)forthisservice... Handler(s): "DEDICATED"established: 11refused: 0state: ready LOCALSERVER "D000"established: 565refused: 4current: 155max: 10000state: ready DISPATCHER helios,pid: 5673> (ADDRESS=(PROTOCOL=tcp)(HOST=helios)(PORT=38411)) Thecommandcompletedsuccessfully. Undernormalconditions,thenumberrefusedshouldbezero.Shutdownthelistenerandrestartittoerasethesestatistics.Iftherefusedcountisincreasingafterthelistenerrestarts,thentheconnectionsarebeingrefused.Iftherefusedcountstaysatzero,andiftheproblemyouaretroubleshootingisoccurring,thenyourproblemisnotwiththeconnectionsbeingrefused. CheckingtheConnect/SecondRate Connectionrefusalscanoccurformanyreasons.Examinethelistenerlogtoseewhattheconnectrateis.Runthelistenerloganalyzerscripttocheck. Thelistenerisaqueue-basedprocess.Itreceivesconnectrequestsfromthelowerlevelprotocolstack.Ithasalimitedqueuestackwhichisconfigurabletotheoperatingsystemmaximum.Itcanonlyprocessoneconnectionatatime,andthereisalimittothenumberofconnectionsasecondtheprocesscanhandle. Iftherateatwhichtheconnectrequestsarriveexceedsthatlimit,thentherequestsarequeued.Thequeuestackisalsolimited,butyoucanconfigureit.Iftherearemorelistenerprocesses,thentherequestsmadeagainsteachindividualprocessarefewerandarehandledmorequickly. Increasingthelistenerqueueisdoneinthelistener.orafile.Thelistener.orafilecancontainmanylisteners,eachbyadifferentname.Itisassumedthatonlyoneofthoselistedishavingaproblem.Ifnot,thenapplythismethodtoallapplicablelisteners.Toincreasethelistenerqueue,add(queuesize=number)tothelistener.orafile.Forexample: listener= (address= (protocol=tcp) (host=sales-pc) (port=1521) (queuesize=20) ) SeeAlso: OracleNetServicesAdministrator'sGuide Stopandrestartthelistenertoinitializethisnewparameter.Ifyouarenotcurrentlyrunningasharedserverconfiguration,thenconsiderdoingso.Itisfasterforthelistenertohandleaclientrequestinasharedserverconfigurationthanitisinadedicatedserverconfiguration. Note: Sharedserverdispatchersalsoreceiveconnectrequestsandcanalsobenefitfromtuningthequeuesize. Themaximumqueuesizeissubjecttothemaximumsizepossibleforaparticularoperatingsystem. DetectingNetworkProblems Thissectionencompasseslocalareanetwork(LAN)andwideareanetwork(WAN)troubleshootingmethods. UsingDynamicPerformanceViewsforNetworkPerformance Networksentailoverheadthataddsacertainamountofdelaytoprocessing.Tooptimizeperformance,youmustensurethatyournetworkthroughputisfast,andyoushouldtrytoreducethenumberofmessagesthatmustbesentoverthenetwork.Itcanbedifficulttomeasurethedelaythenetworkadds. Threedynamicperformanceviewsareusefulformeasuringthenetworkdelay: ∙V$SESSION_EVENT ∙V$SESSION_WAIT ∙V$SESSTAT InV$SESSION_EVENT,theAVERAGE_WAITcolumnindicatestheamountoftimethatOraclewaitsbetweenmessages.Youcanusethisstatisticasayardsticktoevaluatetheeffectivenessofthenetwork. InV$SESSION_WAIT,theEVENTcolumnliststheeventsforwhichactivesessionsarewaiting.The"sqlnetmessagefromclient"waiteventindicatesthatthesharedorforegroundprocessiswaitingforamessagefromaclient.Ifthiswaiteventhasoccurred,thenyoucanchecktoseewhetherthemessagehasbeensentbytheuserorreceivedbyOracle. Youcaninvestigatehang-upsbylookingatV$SESSION_WAITtoseewhatthesessionsarewaitingfor.Ifaclienthassentamessage,thenyoucandeterminewhetherOracleisrespondingtoitorisstillwaitingforit. InV$SESSTATyoucanseethenumberofbytesthathavebeenreceivedfromtheclient,thenumberofbytessenttotheclient,andthenumberofcallstheclienthasmade. UnderstandingLatencyandBandwidth Themostcriticalaspectsofanetworkthatcontributetoperformancearelatencyandbandwidth. ∙Latencyreferstoatimedelay;forexample,thegapbetweenthetimeadevicerequestsaccesstoanetworkandthetimeitreceivespermissiontotransmit. ∙Bandwidthisthethroughputcapacityofanetworkmediumorprotocol.Variationsinthenetworksignalscancausedegradationonthenetwork.Sourcesofdegradationcanbecablesthataretoolongorwrongcabletype.Externalnoisesources,suchaselevators,airhandlers,orflorescentlights,canalsocauseproblems. CommonNetworkTopologies LocalAreaNetworkTopologies: ∙Ethernet ∙FastEthernet ∙1GigabitEthernet ∙TokenRing ∙FDDI ∙ATM WideAreaNetworkTopologies: ∙DSL ∙ISDN ∙FrameRelay ∙T-1,T-3,E-1,E-3 ∙ATM ∙SONAT Table 11-1liststhemostcommonratingsforvarioustopologies. Table11-1 BandwidthRatings TopologyorCarrier Bandwidth Ethernet 10Megabits/second FastEthernet 100Megabits/second 1GigabitEthernet 1Gigabits/second TokenRing 16Megabits/second FDDI 100Megabits/second AT
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