SAP Library - Find your answers

Symptom:

Various error messages that refer to memory bottlenecks (a swap space bottleneck), for example: System Panic; cmemreserve: reservation overrun; ENOMEM, Not enough core; ENOSPC, No space left on device; SIGDANGER (only under AIX). In the R/3 System, the R/3 system log message "no memory of class perm" is output.

This problem can occur with R/3 processes and external processes as well. The relevant process cannot allocate anymore heap memory. This can lead to the database operation being ended or R/3 work processes being stopped.

In the R/3 System, error messages appear in the developer trace files dev_disp, dev_w, in the system log and in dumps. The following messages may appear: TSV_TNEW_; _NO_ROLL_MEMORY; NO_MEM; NO_MEMORY; RESIZE_EM_ALLOC_ERROR, Storage class PERM.

This problem mostly occurs if background jobs are active with large amounts of data.

Possible Causes

• There is no more swap space available (see
Alert Monitor).
• The highest value for one of the R/3 profile parameters that limit the swap space usage has been exceeded. In this case, the following parameters are relevant:
abap/heap_area_dia, abap/heap_area_nondia and abap/heap_area_total.
• The operating system limits for the process size (segment size) have been exceeded. Under AIX, no more than 256 MB can be allocated and under SINIX no more than 384 MB can be allocated.

Corrective action

Increase the swap space or decrease the R/3 Extended Memory. If the swap space already corresponds to the SAP recommendations, 1.5 to 2 GB may still be required. There should always be several hundred MB of free swap space available. You can reduce the maximum swap space need of the R/3 System by reducing the value of parameter abap_heap_area_total. For more detailed information, see Monitoring the Memory Management System.

You can also distribute the load onto several application servers and increase the roll area. Check if the maximum process size (operating system parameters) is sufficient.

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:

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.