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SWAP

Former Member
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Hello Gurus

Can Anybody Tell Me What is the Term SWAP Means ?

A Brief Description About SWAP

And Why it is showing Red when we perform T-code - ST02

Accepted Solutions (0)

Answers (2)

Answers (2)

Former Member
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Hi,

SWAP is the amount of page space available at OS level.In case of windows it should not be more than 4 times the ram and in case of Unix 3 times the raam.If swap or paging is configured high is the paging rate and low is the performance..If there is no more free directory entries are available in the buffer for new objects, old objects are removed and the space is occupied by new objects thus a swapping takes place ie some buffer content is removed from the buffer and replaced by new buffer contents. HIgh swap is normally a symptom of memory bottleneck.

Red indicate swaps are to be avoided. and indicate that there might be a bottleneck.

Hope this helps.

Regards

Former Member
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he was referencing ST02 which is an overview for ABAP servers memory caches.

has nothing to do with Operatings systems pagefiles.

peter

Former Member
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regarding your question placed in the forum the solution for the question are

SWAPS are nothing but repacing of objects from the buffer.

if the swap buffer is full ,the to get the new objects in the buffer it will replace the old objects by taking out from the buffer and place the new objects in that place which can be used by the user . thus the swaps occure.

we have to look in that there should be not more than 10000

in st02 we look in the HIT ratio, it should be 90%, if it is 70% then we have to tune

it

we have to look into the role area,and page area and theheap memory

heap memory area should not be used it should "0"

Former Member
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the number of swaps may be an indicator that a buffer is too small.

But be cautious: the essential parameter for the question to increase a buffer is the buffer quality (also sometimes named hitration) not the number of swaps.

depending on the ABAP Server version it makes no sence to raise the buffer over a certain limit (ABAP Server < 640 can only utililize a program buffer up to about 650 MB). If you size it bigger then it is not used and you waste virtual memory for it (on 32 Bit Windows).

Be carefull with raising buffers on 32 Bit Windows. Raising buffers will automatically consume virtual memory which will shorten the amount of memory a ABAP report is able to allocate!

>>heap memory area should not be used it should "0"

that is not correct.

there is no heap memory area you can configure. An ABAP report allocating memory will first allocate extended memory (that is memory from a shared area) up to a configurable size (default: 32 Bit ABAP about 400 MB, 64 Bit ABAP about 2 GB), after reaching this limit it will continue to allocate heap memory until reaching a configurable limit. 32 Bit Windows ABAP heap allocation is not limited by a parameter but by max. virtual memory size of a process. The max. Heapsize is something between 50 MB and 2.5 GB, depending on your shared memory configuration of the system and the max virtual address size of the platform (2 GB, 3 GB - if /3GB is set in boot.ini, or 4 GB if running 32 Bit apps on X64 operating system).

In a 64 Bit Kernel the maximum allocatable Heap Memory typically depends on the abap/heap_area_* parameters, (default: Dialog WP 2GB, other WP: not limited, but all WPs at a time PHYS_MEMSIZE/2).

Peter