Re: 6.0 Shared Memory Usage
From: jvemo@cyberspace.com (Jon C. Vemo)
> There are (I believe there also in ver. 6) $ONCONFIG parameters to control
> the amount memory that OnLine can consume. If these are not set (in
> particular SHMTOTAL), then SHM will grow until there's no more room to grow
> - potentially.
"If OnLine tries to allocate another shared memory segment because a
session needs more memory and the SHMTOTAL limit is reached, the task
for which the session needed memory will fail." (Online Performance
Tuning)
So, if I set SHMTOTAL (w 6.0), at some point some of my process will
start failing. I can monitor shared memory usage and
shutdown/restart Online when it *gets close*, but, at best, this is
not as graceful as 5.0.
> >We have experienced the same behavior during a benchmark on
> >HP-UX (w 7.1) where shared-memory usage approached 1GB.
> >(Luckily we had 2 GB in the box, and 3 GB of swap, so no problem, 8:) )
>
> Check your documentation with the version 7.1 product. You CAN control the
> amount of memory consumed by OnLine. You also now, under this version, have
> the ability to drop free'd segments.
>
> Jon
>
I'm surpised to hear this as we had three (3) Informix reps assisting
us in the benchmark (w 7.1) and all stated that (other than SHMTOTAL) there was
nothing you could do... I just found in the manuals 'onmode -F'
which frees unused memory segments. Sigh, RTFM.
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