CA IDMS Buffer Tuning

World®’16

CAIDMS™BufferTuning

JohnSiraco,Director,SoftwareEngineeringCATechnologies

MFX106S

MAINFRAMEANDWORKLOADAUTOMATION

2 ©2016CA.ALLRIGHTSRESERVED.@CAWORLD#CAWORLD

©2016CA.Allrightsreserved.Alltrademarksreferencedhereinbelongtotheirrespectivecompanies.

Thecontentprovidedinthis CAWorld2016presentationisintendedforinformationalpurposesonlyanddoesnotformanytypeofwarranty. The informationprovidedbyaCApartnerand/orCAcustomerhasnotbeenreviewedforaccuracybyCA.

ForInformationalPurposesOnlyTermsofthisPresentation


Abstract

Thissessiongivesyouanoverviewofdatabaseandjournalbuffersandhowtheywork,aswellashowtotuneyourbuffersforperformance.YouwilllearnhowtosizeyourdatabaseandjournalbufferpoolsforperformanceandhowtotunebufferstoimprovezIIPusage.

JohnSiraco

CATechnologiesDirector,SoftwareEngineering


Agenda

DEFININGANDCHANGINGADATABASEBUFFER

DEFININGAJOURNALBUFFER

ZIIPPROCESSING

THEDIFFERENCEBETWEENDATABASEANDJOURNALBUFFERS

HOWBUFFERSWORK

RECOVERY

1

2

3

4

5

6


DefiningaDatabaseBuffer

§ Bullet1,Calibriregular24pt– Sub-bullet,Calibriregular20pt

§ Sub-sub-ullet,Calibriregular18pt– Sub-sub-subBullet,Calibri

regular16pt

§ Sub-sub-sub-subBullet,Calibriregular16pt


DCMTDisplayBufferDEFAULT_BUFFER


DCMTDisplayBufferDEFAULT_BUFFERLOC


DCMTVaryBufferDEFAULT_BUFFERMAX100000


DCMTVaryBufferDEFAULT_BUFFERINI20000


DCMTVaryBufferDEFAULT_BUFFERADD10000


DCMTVaryBufferDEFAULT_BUFFERCLOSE


DCMTVaryBufferDEFAULT_BUFFEROPEN


DCMTVaryBufferDEFAULT_BUFFER40000


DefiningaJournalBuffer


DCMTDisplayBUFFERJNL_BUFFER


DCMTDisplayBUFFER


DatabaseandJournalFilesandBuffers


DatabaseFilesandBuffers


JournalFileandBuffers


DatabaseReadIntobuffer


DatabaseUpdateinBuffer


AfterImageisBuiltinJournalBuffer


WritetoJournal


WritetoDatabase


DatabaseUpdate,AllBuffersHave‘Mustwriteswitch’Set


DatabaseUpdate,WriteJournalFirst


JournalBufferandI/O


JournalI/O


DCMTDisplayBuffer

ThisshowsuponaDCMTDisplayBuffer,orDCMTDisplayBufferjournal-bufferas:WaitsonpriorI/O3:


JournalI/OErroronRBN100

§ StopJournaling§ SetHighRBNto99§ Swaptothenextjournal§ CAIDMS™takesjournalbuffersforRBN100– 107andwritestothe

newjournal§ Restartjournaling


JournalI/OErroronRBN100

§ Whenrecovery,eitherautomaticrecoveryorwarmstart,ortheArchiveJournalreadstheoldjournal,itwillstopatRBN99

§ TheywillnotreadRBN100§ EventhoughRBN102,103and105weresuccessfullywrittentotheold

journal,thehighRBNof99willstopCAIDMSfromaccessingRBNs102,103and105


DCMTDisplayBuffer

ThisshowsuponaDCMTDisplayBuffer,orDCMTDisplayBufferjournal-bufferas:Waits0


DCMTDisplayBuffer

§ Ifyouhave8journalbuffers,andallarewaitingforI/O,the9thtransactionwillwaitforajournalbuffer.

§ ThisshowsuponaDCMTDisplayBuffer,orDCMTDisplayBufferjournal-bufferas:Waits1


JournalBufferandI/O

§ IftheWaitcountisanythingbut‘0’,thenaddbufferstothejournalbuffer§ Anadditional1or2makeatremendousdifference


JournalI/O

§ IfWaitsonPriorI/Oishigh,thenthebottleneckismostlikelythejournalitself

§ TheI/Oistakingtoolong- addingbufferstotheJournalBufferwillNOThelpthesituation

§ Talktothesystem’sgroup,andseeiftheI/Ospeedtothejournalcanbeimproved


JournalBufferPool- Recovery


DCMTDisplayBuffer


JournalBufferPoolRecovery§ Recoverywilllookinthejournal

buffersfirst,toseeifthejournalimagesarestillinthebuffers

§ Iftherearemorejournalimagesthatarenotinthebuffers,CAIDMSwillreadthejournalbackwards

§ MostDASDisCachedatthedevicelevel– Cacheworkslikeabufferpoolhowever,itisbuilttoworkinaforward

direction,notbackwardslikerecovery– Warmstart willreadthejournalbackwards– Makesureapplicationsissuecommits,sowarmstart doesnothavetoread

manyblocksbackwards


zIIPProcessing

§ TheonlyprocessingdoneinTCBmodeis:– I/O,SVCexecution,andUserModecode

§ ADS,COBOL,DBProcedures,SYSTEMExits

§ Allotherprocessingisdoneonthespecialtyprocessor(zIIP)

§ ByreducingI/O,youwillincreasezIIP utilization

§ IncreaseDatabaseBufferswherepossible


Summary

§ IncreaseDatabasebufferstoreduceI/O

§ IncreaseJournalbufferstohelprecovery

§ ReducingI/OwillhelpzIIPprocessing


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CA IDMS Buffer Tuning

Technology

Transcript of CA IDMS Buffer Tuning