Tuesday, October 6, 2015

SAP ABAP Buffers - Tracking simple changes through a worksheet

There are somethings in Basis that are just not that fun to work on. One is the monitoring and updating of ABAP buffers. So what I've done is add the buffers most likely to swap into this spreadsheet so I can track as needed.

 I've also grouped the buffers to roughly match the screen in ST02.

What I generally do is compare the current buffer settings to a baseline system. In this case I've pulled the sized for a mid-sized system that I worked on a few years ago. Then I update the next column with the current state of the buffer. Here I just want to record if the buffer is swapping so I can identify it as a candidate for re-sizing.

Once I've identified the candidates for changes, I'll estimate how much a buffer should be increased. If a buffer isn't swapping much, I'll increase about 5%. If it is increasing quite a bit I'll go up as high as 25%.

Here are a couple of examples of what I have done in the past:

Initial Record Buffer [rsdb/ntab/irbdsize]
Status: This buffer is swapping and should be increased (15%)
Action:  increase from 12000 to 13800

Program buffer [abap/buffersize]
Status: This buffer  stays below the 10000 swap daily threshold
Action: keep the same size 2331000

CUA Buffer [rsdb/cua/buffersize]
Status: Swapping on this buffer has increased substantially and it needs to be larger (15%)
 Action: 20000> 23000

Notice that I not increasing the sizes by large amounts because I don't want to chase temporary increases in swapping for specific buffers.  Make your changes small and review over a period of months and not weeks or days.

With the spreadsheet above, I'll create additional columns for each time I make a change. That way I can see over a longer time period if the buffers are performing better.