More shmmax questions

[Sunny K]

In the forums messages I gather that for 32-bits applications we must not set shmmax to more than 4GB. I am having a Oracle 817- 64bit running with SAP 3.1 which is 32bit. I have 4 gb of ram and 12 gb of swap. I have set the shmmax to 10gb. I am wondering if this setting will cause any problem for the 32bit SAP. Any advise? BTW the os is HP-UX11-64bits

[Sridhar Bhaskarla]

Hi,

This is only a limit that you impose to your processes for the use of shared memory on the system.

For 32-bit systems, with SHARE_MAGIC, you can get upto 1.75GB of shared memory on the box. However,since each quadrant is of only 1 GB size so is the max for the shmmax parameter.

As 64bit systems since each quadrant is of 1 TB, you can set it to bigger sizes for 64bit applications. Your 32bit applications are still limited to 1.75 GB (SHARE_MAGIC) with a maximum size of 1 GB.

-Sri

[V.Tamilvanan]

Hi,
Definitely this setting won't create any problem. The only drawback by using 32 bit SAP on 64 bit oracle and 64 bit HPUX is your sap application will have a limitation of SHARE_MAGIC executable text to 1 GB and data to 1 GB. The total amount of shared virtual address space by any sap application in the system is limited to 1.75 GB.

For more information. go through /usr/share/doc/mem_mgt.txt and /usr/share/doc/mem_wndws.txt files on HP-UX 11.0 system.

HTH