SAP Memory Management

SAPMemoryManagement anoverview [email protected]

SAPMemoryManagement SAPMemoryareasoverview: § SAPBuffer § SAPRollMemory § SAPExtendedMemory § SAPHeapMemory § SAPPagingMemory § FixedLocalMemoryoftheSAPworkProcess MainfactorsinconfiguringSAPMemory: u PhysicalMainMemory(RAM) àgiveaIenJontoraJobetweenphysicalandvirtualmemory u OperaJngsystemopJonsandrestricJons àcomparebetween32and64bitsystemarchitecture

MemoryManagementFundamental Theword“memory” àvirtualmemory àphysicalmainmemory+swapspace àlocalmemory+sharedmemory Themaximumamountofvirtualmemorythatcanbeallocatedislimitedbytwovariable: § ResultofphysicalhardwarerestricJon § MaximumaddressspacepermitedbyoperaJngsystem TheOperaJngSystemmanagestwotypeofmemory: u Localmemory àallocatedpreciselytooneoperaJngsystemprocess u Sharedmemory àaccessibletomulJpleoperaJngsystemprocess

UserContext Reffered: Ø DatawhichisgeneratedbytransacJonprocess Ø Variables,nternaltable&screenlist Ø Newsesion=newusercontext Ø Dataisstoredindependentlyindifferentmemoryareas Ø StoredinSAProllmemory,SAPextendedmemory,&SAPHeapMemory Sesionsdivideinto: q Externalsesionàopenedexplicitlybyuser q nternalsesionàopenedimplicitlybyprogram submit,calltransac.on,calldialog,callscreen,callfunc.oninupdatetask,callfunc.onin backgroundtask,andcallfunc.onstar.ngnewtask

ProcessFlow Pres. server

SAP ApplicaJon Sever

DB Server

Table buffer Program SAPExtendedMemory

      I       U       G       P       A       S

Dispatcher Queue

     r      e        h      c       t      a      p      s       i        d

buffer

Database

DDCBuffer

buffer

SAPRollMemory WorkProcess

DBProcess

WorkProcess

DBProcess

WorkProcess

DBProcess

SAPRollMemory LocalSAPRollareaofworkprocess § TheiniJalpartofusercontextstored § EachSAPworkprocesscanonlyaccessitsownrollarea SharedSAPRollArea § Accessibletoallofinstanceworkprocesses § Buffertotemporarykeepusercontextwhenauserisassignedtonewworkprocess

Rollin

àcopyingusercontextfromsharedrollareatolocalrollarea

RollOutàcopyingusercontextfromlocalrollareatosharedrollarea

Roll buffer (shared memory) Roll area (local)

Roll area (local) copy

copy

Work Process1

Roll file (disk)

Roll Buffer (shared)

ztta/roll_first Roll (local) ztta/roll_area

Work Process2

rdisp/roll_SHM

Roll In / Roll Out Roll file

rdisp/roll_MAXFS

SAPRollAreaParameters zIa/roll_first àfirstamountofrollareausedinadialogworkprocess zIa/roll_area àsizeofthelocalSAPRollareaintheworkprocess rdisp/ROLL_SHM àsizeofSAProllBuffer rdisp/ROLL_MAXFS àsizeofenJresharedSAProllarea

SAPExtendedMemory o

o

o

o

Sharedmemorywhichmostlyofusercontextstored AllSAPworkprocesscaneditstoredusercontextdirectly Rollinratheronlycopiedtheaddress(pointer)ofwhereausercontextlocatedontheSAP extendedmemory Makesrollprocessmuchfaster

em/initial_size_MB

ztta/roll_extension

SAPExtendedMemoryMainParameters em/iniJal_size_MB à sizeofSAPextendedmemoryallocatedwhentheSAPinstancestarts up em/blocksize_KB à sizeblockwhichsplitSAPExtendedMemory zIa/roll_extension à maximumsizeofausercontextintheSAPExtendedmemory

SAPHeapMemory § §

Areawhichallocatedvariablyaslocalmemoryasrequired. ReleasedaeratransacJoniscomplete.

SAPHeapMemoryMainParameters abap/heap_area_dia à quotasofSAPheapmemorythatadialogprocesscanallocated. abap/heap_area_nondia à quotasofSAPheapmemorythatanondialogprocesscanallocated. abap/heap_area_total à sizethatcanbeallocatedintotalbyallworkprocess. abap/heaplimit à workprocessrestartlimitofheapmemory.

Heap Memory (local)

abap/heap_area_(non)dia abap/heap_area_total

Sequenceinwhichmemoryisallocated (dialogworkprocess) User Context UserIndependent Data

1

2

3

4

Roll memory to

Roll memory to

Roll memory to

Roll memory to

zttz/roll_first

zttz/roll_extension

zttz/roll_area

abap/heap_area_dia

Copying data during context change

Mapping the data during context change

- Data stays in work process - No context switch possible - Work process in private mode

Sequenceinwhichmemoryisallocated (non-dialogworkprocess) User Context UserIndependent Data

1

2

3

Roll memory to

Roll memory to

Roll memory to

zttz/roll_area

abap/heap_area_dia

zttz/roll_extension

Copying data during context change

Mapping the data during context change - Data stays in work process - No context switch possible - Work process in private mode

SAPExtendedGlobalMemory Datacanbestoredgloballybetweenusercontext q Usedtostoredataacrossusercontext q Allowsfast&copy-freeswitchingbasedonmapping. q SubstractedfromSAPExtendedMemorytocalculatetheremainingstorage space q Configuredusingem/global_area_MBparameters q

SAPPagingMemory ObjectthatstoredintheSAPPagingMemory: § ABAPdataclusterstoredtemporarilywithABAPstatement MPORT/EXPORTFROM/TOMEMORY §

§

ParametertransferredwhenprogramsandtransacJoncalled SUBMTREPORT,CALLTRANSACTON,CALLDALOG,CALLSCREEN,CALLFUNCTONNUPDATE TASK,CALLFUNCTONBACKGROUNDTASK,CALLFUNCTONSTARTNGNEWTASK DataextractscreatedbystatementEXTRACT(uptobasis4.5)

SAPPagingMemoryMainParameters: rdisp/PG_MAXFS àsizeofSAPPagingMemory àsizeofSAPPagingBuffer(sharedmemory) rdisp/PG_SHM o o

ErrorcausedbySAPPagingMemory: u TSV_TNEW_PG_CREATE_FALED u SYSTEM_NO_MORE_PAGNG

GlobalvsLocalMemory Server 

Global Memory (shared memory)

Local memory

SAP buffers

 Additional local

(contains e.g SAP Programs)

heap memory (if required)

SAP roll buffer  Extended Memory SAP paging buffer 

(User Context)

Local

Local

Local

memory

memory

memory

1:1

1:n SAP Roll File SAP Paging File

Work

Work

Work

Process

Process

Process

Configuring&MonitoringSAPMemory Areas MainObjecJve: Ø Performance Ø Stability MainFactorstobeconsidered: Ø PhysicalMainMemory(RAM) Ø SwapspaceorpagingfileoftheoperaJngsystem Ø OperaJngsystemrestricJon

NextPointtobeConsidered TotalMainMemoryRequirement q NumberofComputer q SeveralSAPinstancespercomputer q SAPextendedmemoryandrollbuffer q MemoryforSAPworkprocess q Databasenstance q

ZeroadministraJonmemorymagement: PHYS_MEMSZEparameterdefineshowmuchofacomputer’stotalphysical memoryshouldbeusedfortheSAPinstance.

AddressSpaceRestricJon(UNX) em/initial_size_MB User Context

User Independent WP Local

abap/heap_area_(non_)dia

SAP

Roll

SAP Extended Memory

SAP Heap Memory

Buffers

Memory

(Shared)

(local)

(Shared)

(Shared)

 Address Space SAP Work Process

AddressSpaceRestricJon(Windows) em/initial_size_MB SAP Extended Memory Total

em/address_space_MB User Context

User Independent WP Local

abap/heap_area_(non_)dia

SAP

Roll

SAP Extended Memory

SAP Heap Memory

Buffers

Memory

(Shared)

(local)

(Shared)

(Shared)

 Address Space SAP Work Process

AssistanceWithTroubleshooJng ErrorbecauseofincorectmemoryareaconfiguraJon: § OperaJngSystemcannotstartbecausetheoperaJngsystemcannot providetherequstedmemoryarea § SessionterminaJonsàuserisloggedoff § ABAPProgramterminaJon. Fourerrorfactors: Ø Programerrors(e.gendlessloop) Ø SAPProfileparametersaresetincorectly Ø TheSwapSpaceontheoperaJngsystemisnotlargeenough Ø ConfiguraJonparametersoftheoperaJngsystemaresetincorectlyorOS limitshavebeenreached.

ABAPProgramTerminaJon ²

²

²

²

²

²

²

²

Thememoryofusercontextisusedup STORAGE_PARAMETERS_WRONG_SET,SYSTEM_ROLL_N_ERROR,TSV_TNEW_BLOCKS_NO_ROLL_MEMORY, TSV_TNEW_PAGE_PAGE_ALLOC_FALED,TSV_TNEW_NDEX_NO_ROLL_MEMORY SystemcannotcreatetheprogrambufferbecausethereisnotnotsufficientsharedmemoryatthatJme PXA_NO_SHARED_MEMORY TheProgramencountersamemoryboIleneckduringanoperaJoninthedatabaseinterface DBF_RTAB_NO_MEMORY,DBF_RSQL_NO_MEMORY TheProgramencountersamemoryboIleneckduringsorJng. EXSORT_NOT_ENOUGH_MEMORY AIemptocreateerrorlogfailsaeraterminatedprogramduetolackofmemory. RABAX_CALLNG_RABAX TheSAPpagingmemoryisusedup SYSTEM_NO_MORE_PAGNG,TSV_TNEW_PAGE_ALLOC_FALED ThememoryforSET/GETparameter(SPA/GPAmemory)isusedup. SET_PARAMETER_MEMORY_OVERFLOW Volumelimitofmemoyallocatedtosinglecall(zIa/max_memreq_MB)issettoolow SYSTEM_NO_ROLL