em/initial_size_MB / Physical RAM

[#1]

Hello,

I have a client who is experiencing some performance issues so I'm just reviewing the memory parameters/allocations.

Environment is Windows/SQL.

The box has 8GB of physical memory with 24GB of virtual memory.

em/initial_size_MB is set to 10GB.

I have in the back of my mind that em/initial_size_MB should not be greater than the amount of physical memory.  Is that correct? And if it's set to a higher value, what issues could it cause?

Many thanks.

[Former Member]

Hi Paul,

em/initial_size_MB value should never be more the physical memory available to the SAP instance.

PHYS_MEMSIZE:

If you have only SAP instance running on the host than you don't need to set the value for it.

Else set it accordingly to available space

Formula:

PHYS_MEMSIZE = Available main memory for the SAP instance

The default value for PHYS_MEMSIZE is the size of the main memory in MB, that is, it is adjusted automatically when the main memory configuration is changed.

em/initial_size_MB  = [PHYS_MEMSIZE]

If required, the extended memory extends itself by the value [PHYS_MEMSIZE / 2].

Example: Application server with 1 GB main memory.

PHYS_MEMSIZE is not maintained and its default value is the size of the main memory. This means that the initial size of the extended memory = 1 GB. If this size is not sufficient, the extended memory is increased in 500 MB steps until the maximum size em/max_size_MB (default: 20 GB) is reached or until there is no more address space in the NT page file.

Hope this helps you out.

Regards,

Prithviraj