32 bit app on aix 6.1

UNIX AIX
1

We have our in house developed software running on AIX 6.1 (6100-06-06-1140). The application is a 32 bit application and the operating system is 64 bit. We are running this application without any issue on AIX 5.3 32-bit on P5. We are facing issue with this application after moving on P7 with aix 6.1.
The application runs for the almost 2 to 3 hours and then crashes generating core dump. The application team is saying there is an issue with memory allocation for 32 bit application on 64 bit OS. We have checked vmstat and found no memory bottleneck. We have inserted an entry in the .profile of the owner of that application which is as below.

export LDR_CNTRL=PREREAD_SHLIB@MAXDATA=0xD0000000@DSA
export EXTSHM=ON
export JIMSHMATNUM=0

After putting these entries application starts working but application vendor insisting on AIX 5.3 32 bit to be installed on P7. We would like to know if there are any settings needs to be done on os to run 32 bit application and what are the above entries mean and what impact they are having on the system.

regards,

vjm

2

Hi

please see here

I guess you won't have any benefit it downgrading to AIX 5.3 32bit as the shared memory model is exactly the same and your application simply struggles because of insufficient memory segments.

3

So what do I suppose to do now, please suggest.

regards,

vjm

4

Why do they still feel the need to do anything if it works now

Running a 32bit OS on p7 doesn't sound like a reasonable idea to me and AIX 6.1 is pretty well downwards compatible when you are opening the shared memory section

5

"zxmaus"

The application crashed again yesterday. That's why they want 5.3.

And is there any memory related difference between 5.3 and 5.2.

please suggest.