Stefan.Gabriel@nylex.com.au wrote:

> Hi all,
>
> I have a question regarding the virtual memory portion of informix shared
> memory. What is the comparison between the size of the resident memory
> compared to the size of the virtual memory? i.e, if the resident portion is
> 700MB, what should the virtual portion be?

This depends much on what is going on. I know installations with 3 or 4
configurations. Fx one configuration for data loading - here almost all
memory is allocated to BUFFERS (resident shared memory), another
configuration for index build allocates most of the memory for virtual
shared memory and a third configuration with almost even split between
resident and virtual for "normal" production.

>
> This for a db/CI server running informix 7.31.TD1X2 on Windows 2000 SP4
> with 4GB physical memory and 10GB pagefile. Resident memory is at 175000
> buffers (700MB), currently virtual portion is 400MB. I am seeing that the
> virtual portion has been extending up to 6 times a month constantly and am
> looking for recommended values to reduce this extending.

With 4GB memory Windows2K splits the memory into 2 GB system memory and
2GB user memory. You can add the '/3GB' option to the boot line in the
boot.ini file. With this option memory is split into 1 GB system memory
and 3GB user memory. This will usually reduce the os paging.

When the virtual shared memory is growing you should look at the
application. Sometimes an index can reduce the need for vsm, sometimes
you must rewrite sql statements.
If it's a particular app (fx a monthly report) that makes IDS allocate a
lot virtual shared memory, you can often free the memory afterwards with
the 'onmode -F' command.