1. SAP Memory Management (an Overview)
Radityo Yudhiarto /

2. 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 :
Physical Main Memory (RAM)
 give attention to ratio between physical and virtual memory
Operating system options and restrictions
 compare between 32 and 64 bit system architecture

3. Memory management fundamental : The word “memory”  virtual memory
 physical main memory + swap space
 local memory + shared memory
The maximum amount of virtual memory that can be allocated is limited by two variable :
Result of physical hardware restriction
Maximum address space permited by operating system
The Operating System manages two type of memory :
Local memory
 allocated precisely to one operating system process
Shared memory
 accessible to multiple operating system process

4. User Context
Reffered :
Data which is generated by transaction process
Variables, Internal table & screen list
New sesion = new user context
Data is stored independently in different memory areas
Stored in SAP roll memory, SAP extended memory, & SAP Heap Memory
Sesions divide into :
External sesion  opened explicitly by user
Internal sesion  Opened implicitly by program
submit, call transaction, call dialog, call screen, call function in update task, call function in background task, and call function starting new task.

5. Pres. server SAP Application Sever DB Server SAP GUI Process Flow
SAP Extended Memory
Dispatcher Queue
SAP Roll Memory
dispatcher
Table
buffer
Program
DDIC Buffer
Work Process
DB Process
Database
Process Flow

6. SAP Roll Memory
Local SAP Roll area of work process
- The initial 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 : copying user context from shared roll area to local roll area
Roll Out : copying user context from local roll area to shared roll area

7. Roll buffer (shared memory)
Roll area (local)
Roll file (disk)
Work Process1
Work Process2
copy
Roll file
Roll (local)
Roll Buffer (shared)
Roll In / Roll Out
rdisp/roll_SHM
rdisp/roll_MAXFS
ztta/roll_first
ztta/roll_area

8. SAP Roll area parameters
- ztta/roll_first : First amount of roll area used in a dialog WP
- ztta/roll_area : size of the local SAP Roll area in the work process
rdisp/ROLL_SHM : size of SAP roll Buffer
rdisp/ROLL_MAXFS : size of entire shared SAP roll area

9. SAP Extended Memory
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
ztta/roll_extension
em/initial_size_MB

10. SAP Extended Memory main parameters :
em/initial_size_MB : size of SAP extended memory allocated when the SAP instance starts up
em/blocksize_KB : size block which split SAP Extended Memory
ztta/roll_extension : maximum size of a user context in the SAP Extended memory

11. Area which allocated variably as local memory as required.
SAP Heap Memory
Area which allocated variably as local memory as required.
Released after a transaction is complete.
SAP Heap Memory main parameters :
abap/heap_area_dia : quotas oh SAP heap memory that a dialog process can allocated.
abap/heap_area_nondia : quotas oh SAP heap memory that a nondialog process can allocated.
abap/heap_area_total : size that can be allocated in total by all work process.
abap/heaplimit : Workprocess restart limit of heap memory
Heap Memory (local)
abap/heap_area_(non)dia
abap/heap_area_total

12. User-Independent Data
Sequence in which memory is allocated (dialog work process) :
User-Independent Data
Roll memory to
zttz/roll_first
zttz/roll_extension
zttz/roll_area
abap/heap_area_dia 1 2 3 4
User 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

13. User-Independent Data
Sequence in which memory is allocated (non-dialog work process) :
User-Independent Data
Roll memory to
zttz/roll_extension
zttz/roll_area
abap/heap_area_dia 1 2 3
User 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

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

15. 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 transaction 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 :
rdisp/PG_MAXFS : Size of SAP Paging Memory
rdisp/PG_SHM : Size of SAP Paging Buffer (shared memory)
Error caused by SAP Paging Memory :
TSV_TNEW_PG_CREATE_FAILED
SYSTEM_NO_MORE_PAGING

16. Global Memory (shared memory) Local memory
Server
Global Memory (shared memory)
Local memory
SAP buffers
(contains e.g SAP Programs)
Additional local
heap memory (if required)
SAP roll buffer
Extended Memory
(User Context)
Local
memory
Local
memory
Local
memory
SAP paging buffer
1 : 1
1 : n
SAP Roll File
Work
Process
Work
Process
Work
Process
SAP Paging File

17. Configuring & Monitoring SAP Memory Areas
Main Objective :
 Performance
 Stability
Main Factors to be considered :
Physical Main Memory (RAM)
Swap space or paging file of the operating system
Operating system restriction

18. Next points to be considered : Total Main Memory Requirement
Number of Computer
Several SAP instances per computer
SAP extended memory and roll buffer
Memory for SAP work process
Database Instance
Zero administration memory magement :
PHYS_MEMSIZE parameter defines how much of a computer’s total physical memory
should be used for the SAP instance.

19. Address Space Restriction (Unix)
User Independent WP
Local
SAP
Buffers
(Shared)
User Context
Roll
Memory
SAP Extended Memory
SAP Heap Memory
(local)
em/initial_size_MB
abap/heap_area_(non_)dia
Address Space
SAP Work Process

20. SAP Extended Memory Total
Address Space Restriction (Windows)
User Independent WP
Local
SAP
Buffers
(Shared)
User Context
Roll
Memory
SAP Extended Memory
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

21. Assistance With Troubleshooting
Error because of incorect memory area configuration :
Operating System can not start because the operating system
cannot provide the requsted memory area
Session terminations  User is logged off
ABAP Program termination.
Four error factors :
Program errors (e.g endless loop)
SAP Profile parameters are set incorectly
The Swap Space on the operating system is not large enough
Configuration parameters of the operating system are set incorectly
or OS limits have been reached.

22. ABAP Program Termination :
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
System can not create the program buffer because there is not not sufficient shared memory at that time
PXA_NO_SHARED_MEMORY
The Program encounters a memory bottleneck during an operation in the database interface
DBIF_RTAB_NO_MEMORY, DBIF_RSQL_NO_MEMORY
The Program encounters a memory bottleneck during sorting.
EXSORT_NOT_ENOUGH_MEMORY
Attemp to create error log fails after a terminated program due to lack of memory.
RABAX_CALLING_RABAX
The SAP paging memory is used up
SYSTEM_NO_MORE_PAGING, TSV_TNEW_PAGE_ALLOC_FAILED
The memory for SET/GET parameter (SPA/GPA memory) is used up.
SET_PARAMETER_MEMORY_OVERFLOW
Volume limit of memoy allocated to single call (ztta/max_memreq_MB) is set too low
SYSTEM_NO_ROLL

23. - End of Presentation -