ST02 SWAPS reported what does that mean.

Question

Hi Team,
In ST02 of one of the system all the apps I see many SWAPS column with value and in red color, what it mean
program, swaps with 11,349
generic key with 68
single record with 1,002
Thanks
Vijay

Answer 1

Hi,
ST02 is the buffer monitor that offers instance specific information that provides:
1. status of different buffers instance wise
2. information on memory usage instance wise
3. information on table buffering at instance level
Swapping takes place for two reasons:
1. not enough 'free space left' in buffer for buffering new objects
2. buffer has run ouf of 'free directory entries' that can be contained in one buffer area *
Directory entries diminish the available size of the buffer, independent of their usage.
Swaps are to be avoided, as are all other situations leading to lines shown in red in the ST02 display.
Please note that Buffer swaps occur when buffer content is deleted from the buffer and is replaced by other content. It has no relation at all to the swapping mechanism on OS level.
An example with a more practical outlook to swapping observed:
Use transactions SM50, ST03N and ST02 to identify the problem.
a. Using SM50 you might find high number of work processes accessing tables related to ABAP sources and status as 'Load Program'. This hints to a problem with Program [PXA] buffer.
b. In transaction ST03N, you find unusually high 'load and generation time' causing even higher wait times. Threshold for load and generation time is typically 50 ms.
c. In buffer monitor i.e. ST02, you find many swaps [typically more than 10000 swaps happening per day for program buffer]. Check on hit ratio [value below 95% is typically poor]. This indicates problem. Program buffer could be small!!
If program buffer is small, it means that workprocesses require to reload program loads over and over again which causes bad system performance.
Resolution: Increase program buffer size/ check on load and generation times/ hit-ratio increases/ system response time also lowers down!! : )
Regards,
Shabnam.