Sap Extended Memory Parameter

ztta/roll_area: Roll area size

  1. Sap Extended Memory Parameter Definition
  2. Sap Extended Memory Parameters
  3. Sap Extended Memory Parameter Example

SAP Extended Memory. SAP extended memory is the core of the SAP memory management system. Each SAP work process has a part reserved in its virtual address space for extended memory (see Virtual Address Space in a Work Process). You can set the size of extended memory using the profile parameter em/initialsizeMB: Extended Memory Pool Size. ST-SER GL1R3CONF: Wrong Parameter Recommendations: 1048686: Recommended AIX settings for SAP: 973227: AIX Virtual Memory Management: Tuning Recommendations: 950845: CST Patch Collection 22 2006: 944284: CST Patch Collection 17 2006: 912425: AIX: Unexplained high memory consumption.


  1. Quota for Extended Memory. Parameter Description. This values specifies the amount of memory in bytes that a user context can allocate to extended memory. The value refers to the amount of memory that an external session (=SAP window) allocates.
  2. Extended memory is used until the extended memory is full or until the user quota is reached; Extended memory is defined by the SAP parameter em/initialsizeMB and the user quota for dialog work process is defined by the parameter ztta/rollextensiondia. If this memory is also not sufficient, then. The rest of the roll area is used.

Description: The value specifies the size of the roll area in bytes. The roll area is one of several memory areas, which satisfies the user requests of user programs. For technical reasons, however, the first 250 KB or so of a user context are always stored in the roll area, further data


- up to the roll area limit ztta/roll_first,


- in the extended memory, up to the limit ztta/roll_extension or If extended memory is exhausted, then

Sap Extended Memory Parameter

- again in the roll area, until the roll area is full, then


Sap Extended Memory Parameter Definition

- in the local process area, up to the limit abap/heap_area_dia


or abap/heap_area_total or until the address space or the swap space is exhausted.


Followed by termination with errors like STORAGE_PARAMETERS_WRONG_SET an error code, that points to memory ottleneck


Aim:


Minimum data transfer with context change; however, the increase helps to avoid problems (address space, swap space, operating system paging)


Unit: Bytes


Dependencies:

Sap Extended Memory Parameters


User

rdisp/ROLL_SHM: Should be adjusted because of ztta/roll_area


rdisp/ROLL_MAXFS: Must be adjusted because of ztta/roll_area can be checked by ST02


ztta/hold_data_area: Buffer for User Set/Get Values

Sap parameter id list

Size of the shared memory buffer for user Set/Get data


(System -> User defaults -> Get/Set).


Use: Tuning.


ztta/roll_extension: Short description: Quota for extended memory


Description:


This value specifies the storage quantity in bytes that a dialog user context can allocate (extended memory). The value refers to the storage quantity that an external mode (=SAP window) allocates. When the specified value is exceeded, memory from the roll area is allocated until this is full. Local memory is then allocated.


( Data in the roll area is copied at context change When local memory within the work process is allocated, the work process is assigned to this user context and is no longer available for other user contexts (PRIV mode).) If you set the value too high, a user could cause a bottleneck in the extended memory by increasing his user context. Other smaller user contexts would bring work processes to PRIV mode before their allowed quota is reached.


Objective: Minimize no. of work processes in PRIV mode. Allocate extended memory fairly.


ztta/roll_first :Quota for early allocation in the roll area


Parameter description :


The value specifies the amount of memory in bytes that is allocated from the roll area, before memory is allocated from the extended memory. This means that small user contexts remain complete in the roll area. Any wastage and therefore total consumption of the extended memory can be minimized, because extended memory is assigned to users in granules of a specific length (usually 1 MB).


Only effective in dialog work processes. (Windows NT) Effective in all work processes, due to identical allocation sequence (Windows NT).


Aim:


Optimum usage of the extended memory


ztta/short_area : Size of short-term memory


Parameter description :


Size of memory available in the short term, i.e. until the next 'rollout'


Sap Extended Memory Parameter Example

Sap extended memory parameters

The value must be at least 7 times the size of ztta/cua_area


Work area: System


abap/heap_area_dia: Heap memory quota for dialog work processes


Description:


Defines the local process memory quota (heap, malloc) for a user context in a dialog work process. The aim is to avoid a swap space bottleneck if a user context becomes too large.