sap memory management
DESCRIPTION
SAP Memory ManagementTRANSCRIPT
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, Internal 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 Internal 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
SAP GU
I
SAP Extended Memory
Dispatcher Queue
SAP Roll Memory
dispatcher
Table
buffer
Program
buffer
DDIC Buffer
Work Process
Work Process
Work Process
DB Process
DB Process
DB Process
Database
buffer
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 file
Roll (local)
Roll Buffer (shared)
Roll In / Roll Out
rdisp/roll_SHM
rdisp/roll_MAXFS
ztta/roll_first
ztta/roll_area
Roll buffer (shared memory) Roll area
(local)
Roll file (disk)
Roll area (local)
Work Process1
Work Process2
copy copy
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 Shared memory which mostly of user context stored o All SAP work process can edit stored user context directly o Roll in rather only copied the address (pointer) of where a user context located on the SAP
extended memory o Makes roll process much faster
ztta/roll_extension
em/initial_size_MB
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 ager 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-Independent
Data Roll memory to
zttz/roll_first Roll memory to
zttz/roll_extension
Roll memory to
zttz/roll_area
Roll memory to
abap/heap_area_dia
1 2 3 4User Context
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-Independent
Data Roll memory to
zttz/roll_extension
Roll memory to
zttz/roll_area Roll memory to
abap/heap_area_dia
1 2 3User Context
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 q 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
SAP Paging Memory Object that stored in the SAP Paging Memory : § ABAP data cluster stored temporarily with ABAP statement
IMPORT/EXPORT FROM/TO MEMORY § Parameter transferred when programs and transacJon called
SUBMIT REPORT, CALL TRANSACTION, CALL DIALOG, CALL SCREEN, CALL FUNCTION IN UPDATE TASK, CALL FUNCTION BACKGROUND TASK, CALL FUNCTION STARTING NEW TASK
§ Data extracts created by statement EXTRACT (up to basis 4.5) SAP Paging Memory Main Parameters : o rdisp/PG_MAXFS à size of SAP Paging Memory o rdisp/PG_SHM à size of SAP Paging Buffer (shared memory) Error caused by SAP Paging Memory : u TSV_TNEW_PG_CREATE_FAILED u SYSTEM_NO_MORE_PAGING
Global vs Local Memory
SAP paging buffer
SAP buffers
(contains e.g SAP Programs)
Extended Memory
(User Context)
Server
SAP roll buffer
Global Memory (shared memory) Local memory
Additional local
heap memory (if required)
Local
memory
Local
memory
Local
memory
SAP Roll File SAP Paging File
Work
Process
Work
Process
Work
Process
1 : n 1 : 1
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 q 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 Instance Zero administraJon memory magement : PHYS_MEMSIZE parameter defines how much of a computer’s total physical memory should be used for the SAP instance.
Address Space RestricJon (UNIX)
User Independent
WP
Local
SAP
Buffers
(Shared)
User Context
Roll
Memory
(Shared)
SAP Extended Memory
(Shared)
SAP Heap Memory
(local)
em/initial_size_MB abap/heap_area_(non_)dia
Address Space
SAP Work Process
Address Space RestricJon (Windows)
User Independent
WP
Local
SAP
Buffers
(Shared)
User Context
Roll
Memory
(Shared)
SAP Extended Memory
(Shared)
SAP Heap Memory
(local)
em/address_space_MB abap/heap_area_(non_)dia
Address Space
SAP Work Process
SAP Extended Memory Total
em/initial_size_MB
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 The memory of user context is used up
STORAGE_PARAMETERS_WRONG_SET, SYSTEM_ROLL_IN_ERROR, TSV_TNEW_BLOCKS_NO_ROLL_MEMORY, TSV_TNEW_PAGE_PAGE_ALLOC_FAILED, TSV_TNEW_INDEX_NO_ROLL_MEMORY
² System can not create the program buffer because there is not not sufficient shared memory at that Jme PXA_NO_SHARED_MEMORY
² The Program encounters a memory boIleneck during an operaJon in the database interface DBIF_RTAB_NO_MEMORY, DBIF_RSQL_NO_MEMORY
² The Program encounters a memory boIleneck during sorJng. EXSORT_NOT_ENOUGH_MEMORY
² AIemp to create error log fails ager a terminated program due to lack of memory. RABAX_CALLING_RABAX
² The SAP paging memory is used up SYSTEM_NO_MORE_PAGING, TSV_TNEW_PAGE_ALLOC_FAILED
² The memory for SET/GET parameter (SPA/GPA memory) is used up. SET_PARAMETER_MEMORY_OVERFLOW
² Volume limit of memoy allocated to single call (zIa/max_memreq_MB) is set too low SYSTEM_NO_ROLL
