SYSTEM_NO_ROLL - ztta/max_memreq_MB

[Former Member]

I am looking to resolve a dump above and doing some ground work.  The error is occuring on a BW extract and we already have the BW consultant on optimizing the packet size, line size and any other avenues from application stand point.

I need quick advise on a parameter - ztta/max_memreq_MB.  As per note 353579, we can increase this parameter. I am wondering how this fits into the whole ABAP Memory management.  SAP help says this parameter is an extended memory parameter.  Does this parameter override ztta/roll_extension and run up till the value of em/initial_size_MB.  Also how do we know, it has any effect. I ask this because, our extraction job dumped and extended memory at the time of dump is Extended memory (EM)........... 2003001336  i..e  1910.2 MB however we have ztta/max_memreq at 2047 MB.  That means this parameter is not in effect otherwise Extended memory should have exhausted around 2047 MB and there abouts.

Any thoughts would be appreciated.

Regards

Kal

[paul_power]

H and Kal,

What are the exact memory details from the system no roll dump in st22 ?

You still need to follow the notes below as there are other parameters
outlined for when ztta/max_memreq_MB is at 2047. However it is still
possible to set a higher value for this parameter although you will get
a warning this can be ignored on a 64 bit system.

353579 - SYSTEM_NO_ROLL

You could try setting ztta/max_memreq_MB to 4096 and ztta/roll_extension to 4G

Please check/follow the instructions provided in the below notes and
check the set value for ztta/max_memreq_MB parameter.

    530741 SYSTEM_NO_ROLL runtime error with delta extraction
    353579 SYSTEM_NO_ROLL

regards,

Paul

[Former Member]

Hi Kal,

Good question.

How I understand it is as follows:

em/initial_size_MB
This is the value SAP allocates as extended memory during startup, this automatically extends if needed up until the max size parameter.

ztta/roll_extension
This value tells SAP the amount of extended memory a single user can use before going into roll/heap.

ztta/max_memreq_MB

"The size of strings and hash tables is limited by the biggest memory block that can be requested in one chunk. This is a maximum of 2 GB and is usually further limited via the profile parameter ztta/max_memreq_MB."

Extract from here: (with further information)

http://help.sap.com/abapdocu_70/en/ABENMEMORY_CONSUMPTION_2.htm

I think the reason why it's dumping before the 2GB limit is because the hashed administration table is also stored there, which is going to also included in this limit.

Regards,
Nick

[Former Member]

Thanks Paul.

The amount of storage space (in bytes) filled at termination time was:

Roll area...................... 5820832

Extended memory (EM)........... 2003001336

Assigned memory (HEAP)......... 2000139344

Short area..................... " "

Paging area.................... 16384

Maximum address space.......... 4294967295

---------------------------------------------------------------------------------------------------------

From the above, I know due diligence has to come from application stand point and we will explore all options on that front first since the extraction is exhausting extended and heap on the current limits.

Also am just wondering whether increasing ztta/roll_extension is the ideal way to go because this is a shared memory and if one user blows away his, other users might enter PRIV even before their permitted quota gets exhausted.  I am looking to extend the heaps - dia,non-dia and setting the total heap much highter, this way extended memory still has some buffer even with multiple users running slightly high loads (100 MBs or 200 MBs) and wont enter PRIV modes quickly.  Ofcourse we have quiet an ok kitty with respect to the main memory(shows around 16 GB in memory with 5 GB current use) but want to explore on ztta/max_memreq_MB and heaps first. 

Also am still unclear on ztta/max_memreq_MB.How would I have visibility of this parameter increase in terms of monitoring. Would it reflect against any of the modes i.e ST02 ->Detail analysis menu -> SAP memory -> mode list  whilst the load is running.

Regards

Kal

[Former Member]

Found SAP note Note 425207 - SAP memory management, current parameter ranges

Point 6

ztta/roll_extension must be smaller than

(4096 - ztta/max_memreq_MB) * 1024 * 1024 - 1

Regards

Kal

[Former Member]

Hi Kal,

Check this note for recommended BW parameter tuning Note 192658 - Setting parameters for BW systems

[Former Member]

Hi Paul,

I also got this dump SYSTEM_NO_ROLL

"Unable to fulfil request for 7762 bytes of memory space"

Memory consumption

Roll.... 8793152

EM...... 3737908672

Heap.... 6000059200

Page.... 24576

MM Used. 9726191536

MM Free. 4067360

I would like to confirm if increasing parameter : ztta/max_memreq_MB have an effect as upon increasing the value from 2048 to 2560. I get a warning and if I want to proceed. What is the effect if I go through with this?

Paul

[paul_power]

Hi Paul,

For SYSTEM_NO_ROLL please see note 353579

"

Increase the value of the parameter

• ztta/max_memreq_MB

The maximum value of the parameter is 2.147.483.647. If a larger value is
set for the profile parameter, the value 2.147.483.647 is used by the kernel and
the system writes a warning message.

"

which is your case

ztta/max_memreq_MB is the limit how much program can get memory

for each time . ztta/roll_extension is the limit how much the program

can get EM memory totally .

What are the current values for

ztta/heap_area_dia

ztta/heap_area_nondia

ztta/heap_area_total

[Former Member]

Hi Paul,

May I know the value 2.147.483.647 in MB? Yes I get a warning whenever I tried to increase the value from 2048 to 2560 of ztta/max_memreq_MB. Please confirm if I will just click proceed or Yes and what is the effect.

I think you are referring to abap instead of ztta?

abap/heap_area_dia = 6000000000

abap/heap_area_total = 60000000000

Will increasing the dia help with resolving the issue.

Paul