SAP Preventing Swap Space Bottlenecks (only UNIX /NT)

By using the following parameters, you can limit the maximum use of the process-specific memory. This in turn limits the maximum use of swap space by an R/3 application server.

Consider the following parameters:

Parameter	Limits the amount of process-specific memory used...
abap/heap_area_dia	...by any particular dialog work process
abap/heap_area_nondia	... by any particular non-dialog work process (background, spool, etc.)
abap/heap_area_total	...by an R/3 application server -- all dialog and non-dialog work processes

You can find more information on the functions of these parameters under Limits for Allocating Heap Memory in Functions of the R/3 Memory Management System.

Normally, only background work processes use a large amount of swap space.

Dialog processes do not usually use a lot of swap space, as long as the following conditions apply:

• The R/3 Extended Memory is not used up (set with parameter
em/initial_size_MB); and
• Not many of the user contexts have exceeded the upper limit for using the Extended Memory (set with parameter
ztta/roll_extension).

The following generally applies: The more main memory that an application server has, the better the performance.