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Increase shared memory for HP/UX 11i/Sybase 12.0.x 32bit

Michael Marsh_1
Occasional Contributor

Increase shared memory for HP/UX 11i/Sybase 12.0.x 32bit

With HP/UX release 10.20 patches PHKL_9076 and PHSS_15380 allowed maximum addressable shared memory to be increased from 1.75 GB to 2.75 GB for SYBASE releases 11.5.x and 11.9.2.

Is there a way increase the maximum addressable shared memory for HP/UX 11i and SYBASE release 12.0.x (32 bit) from limitation of 1.75 GB?
4 REPLIES
Bill Hassell
Honored Contributor

Re: Increase shared memory for HP/UX 11i/Sybase 12.0.x 32bit

This will not be simple. You'll need to consult the memory management and process management documents in /usr/share/doc for the details. It will involve changing the Sybase executables with certain implications.

Note that shared memory is a shared resource. Other processes can render this area heavily fragmented thus preventing a large segment from being located, even though the total is much larger than needed. This is a limitation for 32bit processes regardless of the kernel 'bitness'. When you need gigabytes of shared memory, the process must be recompiled into 64bits or you'll spend a lot of time trying to get things to fit.

A helpful program is shminfo which maps the shared memory area. Get a copy from:
ftp://contrib:9unsupp8@hprc.external.hp.com/sysadmin/programs/shminfo/

Note that you'll have to fix IE on PC's to turn off icon view in ftp (a well known bug). Opera and Netscape have no problems, and you can use plain ftp to get to this server.


Bill Hassell, sysadmin

Re: Increase shared memory for HP/UX 11i/Sybase 12.0.x 32bit

In order to use 2.75 GB of memory in 10.20 you would have to change the binary 'dataserver' from EXEC_MAGIC to SHMEM_MAGIC with the command chatr -M dataserver. I would think that procedure would apply to 11i also. Se the link to an old article about 10.20 from Sybase: http://www.sybase.com/detail?id=1010341

Rgds
Johan

Re: Increase shared memory for HP/UX 11i/Sybase 12.0.x 32bit

No limitation now for HP/UX 11i and SYBASE release 12.0, we are running such a box with sybase totalmemory=12G. Only need to tune some kernel parametres such as SHAMMAX.
Michael Marsh_1
Occasional Contributor

Re: Increase shared memory for HP/UX 11i/Sybase 12.0.x 32bit

Michael Lee,

That's very interesting - we currently have total memory set at 600meg. Any higher the application on the server will not run.

We are running Sybase ASE12.0 - 32bit mode.
Are you running 32bit or 64bit release of Sybase 12.0?

Mike Marsh