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Purpose

List of arithmetical parameters based in hardware resource.

Overview

SAP systems are configured by using profile parameters that consist in a simple parameter name with a value.

Some parameters are related to hardware resources, therefore, these are arithmetical formulas based. This Wiki page intent to maintain a relation of parameters that are hardware based size.

Machine resources

Machine resources that are available for the SAP Application Server are determined by the parameters PHYS_MEMSIZE and CPU_CORES.

Further information about how to setup these parameters see following documentation.

Formula based parameters

Arithmetic formulas can be used in parameter values. further information  about formulas usage see this documentation.

Current parameter sized by hardware resources 

Parameter name Default
abap/heap_area_total    (max($(PHYS_MEMSIZE)*1024*1024 * 0.1,  $(abap/heap_area_dia) * 2 ))
em/initial_size_MB   min(512000, $(PHYS_MEMSIZE) * 0.7))

EM/TOTAL_SIZE_MB

($(PHYS_MEMSIZE) * 0.7)
j2ee/phys_memsize  $(PHYS_MEMSIZE)
rdisp/PG_SHM (max(min(1000+40*max(5,floor(($(PHYS_MEMSIZE)-128)*25/128)),16384),1024))
rsdb/obj/buffersize  (max(4096,$(PHYS_MEMSIZE)*1024 * 0.01))
j2ee/cpu_count $(CPU_CORES)

If the parameter is set in the instance profile or even default profile, the default value is ignored and the profile specific is used.

Conclusion

Using the default defined formulas in SAP parameters facilitate the configuration of an Application Server because less parameters control is required. 
With the definition of PHYS_MEMSIZE and CPU_CORES, parameter value can be derived from hardware resources making the Application Server more reliable as per the available resources.

Related Content

1926986 - Best practice formulas in profile maintenance