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Memory parameters for SAP on 64 bit Windows

With Windows 64 bit the address space restrictions of 3Gb on 32 bit Windows no longer apply.   The boot.ini file on the C drive is no longer used  the /3Gb and /pae swiches are not relevant to 64 bit Windows.  The Windows page file needs to be a least 20Gb it also depends on the RAM you use and the numer of instance on the host note 1518419  The basis for zero administration memory management on Windows is the dynamically self-extending extended memory.The extended memory is initially set to the size of the profileparameter PHYS_MEMSIZE ([PM]). PHYS_MEMSIZE is not a limit for extended memory on Windows the limit is the parameter em/max_size_MB normally set to 100Gb.  If you use parameter  PHYS_MEMSIZE in the instance profile then these parameters are calculated automatically .  

  em/max_size_MB; em/address_space_MB;  

ztta/roll_first;  ztta/roll_area;  ztta/roll_extension;

abap/heap_area_dia;  abap/heap_area_nondia;

abap/heap_area_total; rdisp/ROLL_MAXFS;

rdisp/ROLL_SHM;  rdisp/PG_MAXFS;


However if any of these parameters are set in the instance profile then the instance profile value is used. 


  Memory Management under Windows notes….

1518419 – Page file and virtual memory required by the SAP system

931024 – FAQ: 64-bit platforms for Windows

88416 – Zero administration memory management for the ABAP server

313347 – Windows editions and memory support

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  • OK – so I admit to not chasing down the notes.   But if there are some people on 64 bit and some people on 32 bit, can the parameter PHYS_MEMSIZE be used?

    Sorry for not reading everything before fishing for an answer!  I just don’t want to read everything if it can’t be done.

    Thank you!


          • I haven’t in a while – gotten short dumps.  I’m on a whole new system – new job.  But I used to get roll memory short dumps.  Looking at this, it seems like that would make some of those go away.   I am on a 64 bit system.  But I know some of the people in my company are on 32 bit systems.

  • as of Kernel Version 7.20 em/max_size_MB is set to 1.5 * PHYS_MEMSIZE.

    if PHYS_MEMSIZE is not set in a profile then the default is the RAM Size of the computer.