RAM Upgrade

[Former Member]

Hello everybody hope you can guide me up with this problem i have...

as the title says we just increased our SAP server RAM from 16 GB to 24 GB...why? you may ask..well we were having a lot os dumps regarding NO_PXA_SHARED_MEMORY, MEMORY_GET_BLOCK_ADDRESS, plus we detected something kind of weird....we have a 65 GB page file...but when checking windows task manager is says it usingo almos 80 GB of Page file...kind of weird uh??

so we thought increasing RAM will be the solution...looks like it wasn't the right one...

there were some error about abap buffer size too...somethjing about some swap objetcs...when checking ST02 i got this:

all the reds are about some objects and frames swapped...

anybody have an idea on how attacking this issue??

Thanks everybody in advance !!!

[csaba_goetz]

Hello David,

'PF usage' in Windows task manager represents a summa of RAM+Swap (A.K.A. virtual memory). The question is what uses this huge amount of memory. What I cannot see on the screenshots is the value of abap/heap_area_total parameter. Never set it to value 0 (zero) what would allow unlimited memory usage for SAP. Please check if it is set to zero or to a very high value - if yes, you need to adjust it accordingly. Please refer to SAP note 88416 and SAP note 1639177.

PXA_NO_SHARED_MEMORY dump could be caused by small configured abap/buffersize parameter (you need to increase it, this is the area where lots of swaps occured) or by the intensive and huge memory usage on the server (~80GB) where the operating system wanted to survive and did't allow the applications (in this case for SAP) to use more memory.

Best regards,

Adam

[xymanuel]

Hi Adam, i think his problem is the hugh extendend memory currently allocated.

65GB is very high, and it is not used.

The appserver consumes 6,8GB max.

Regards

Manuel

[csaba_goetz]

Hello David, hello Manuel,

Nearly 65GB for em/initial_size_MB is quite high in fact, but this amount of memory is not allocated at startup - it represents only the upper limit of extended memory (in the first step, see also em/max_size_MB) which is available for all processes together as maximum. So this cannot be the reson of enorm high memory usage.

Best regards,

Adam

[xymanuel]

Hi David,

Please configure the following:

First set PHYS_MEMSIZE in Instanceprofile to 20000 (20GB)

e.g. i set it to 25.000 which is 25 GB on an Appserver with 32GB RAM.

This limits the Appserver to allocate to much RAM.

In your case i would reserve 4GB RAM for the OS.

(If you have your DB Server on the same Host, i would recommend to use

12GB RAM for the DB Server max/min memsize and 8GB for the Appsever (Phys_memsize 8000).

Second e.g. Screenshot of an Appserver with 32GB RAM

Increase your Buffers of the Table definition, Field definition and inital records buffer!!

These Buffers are vital for a stable and fast SAP system.

e.g. Table buffer is 50MB in my screenshot, you have only 6MB (on a server with 24GB RAM... wasted ressources).

Increase Programbuffer to about 1GB (in my case it is 1.5GB).  10.000 Programbufferswas a day can be tolerated.

e.g. parameters for my screenshot

rsdb/ntab/ftabsize   200000

rsdb/ntab/entrycount 150000

rsdb/ntab/sntabsize  3072   kB

rsdb/ntab/irbdsize   60000  kB

rsdb/ntab/entrycount 150000

Extended Memory is limited by the PHYS_MEMSIZE parameter. In my case 25GB.

In your case the maximum use of the extended mem is 6,5GB (in my 12,875).

-> The minimum extended memory u need is 8GB.

(PHYS_MEMSIZE automatically sets extended mem. Do not set it manually if PHYS_MEMSIZE is set

)

Kind regards

Manuel

[Former Member]

Hi Manuel, can you please upload the images again...just can't see them.

i was kind of out the work and wasn't able to check up on this.

thanks.

[xymanuel]

*bahhh* SCN..

Again..

e.g. i set it to 25.000 which is 25 GB on an Appserver with 32GB RAM.

Second e.g. Screenshot of an Appserver with 32GB RAM

(PHYS_MEMSIZE automatically sets extended mem. Do not set it manually if PHYS_MEMSIZE is set

Regards Manuel

[former_member182034]

hi David,

you are getting issue due to parameters because you did not set according to RAM now you have to increase the following parameter respectively.

NO_PXA_SHARED_MEMORY

abap/buffersize  

here you are getting lot of swapping so, you have increase 40% value of abap buffer,  but good practice is that you have to increase the 20 % value and then increase after monitor.

after that you have to increase the remaining parameters.

ABAP dump MEMORY_GET_BLOCK_ADDRESS

first you have to increase the Virtual Memory/ Page file and check following SAP note:

750456 - ABAP dump MEMORY_GET_BLOCK_ADDRESS

Regards,