Re: Oracle 9.2.0.1 swap reservation on hp-ux 11

From: KevJohnP <nospam_at_nowhere.com>
Date: Sun, 01 Dec 2002 10:54:43 +1300
Message-ID: <3DE933A3.4090503@nowhere.com>

Hi Arek

I guess the question is why do you want to disable reserving of swap - what problem is this causing you?

Pseudo swap is just that - pseudo. It does not exist and is not taking any resources. I do not believe it is possible to fully disable reserving swap for processes (this is an operating system function and cannot be changed by an application like oracle), in many ways pseudo swap is there precisely to try and do that.

If you are having memory problems because of the amount of memory used (rather than reserved), then that is a different matter. This would be signalled by paging out activity seen using glance or vmstat. In that case there are things that can be done;

• reducing the size of the sga
• de-installing unused oracle products and relinking
• on hpux it is often worth reducing the unix buffer cache on database servers given that oracle also caches in the sga
• reduce the settings of init.ora parameters that affect the PGA/UGA

etc.

HTH KJP Arkadiusz Malinowski wrote:

>>HPUX by default is configured to use 'pseudo' swap (this can be disabled
>>by setting a kernel parameter if not required).  By default the kernel
>>will take 75% of the physical memory size for the psuedo swap.  As
>>indicated by its name this swap does not actually exist anywhere.  So
>>this may explain the 2GB.
>>
>>Also, checking the size parameter and multiplying by the number of
>>processes is also not a true guide as much of a normal processes size is
>>taken by shared libraries.

>
>
> I tried with swapmem_on=0 it don't work
> Oracle reserve (not use) 2GB of swap memory.
> 59 oracle processes each reserve minimum 16384 pages of swap (chunk 2048) =
> c.a. 2GB
> Do You know how to turn off memory swap reservation? I why each process
> reserve so many pages?
> The biggest process (don't count Oracle ) reserve only 1000 pages.
>
> I don't know if I must change something in Oracle not to reserve so many
> pages or is OS specific (if so can I change this deafault behavior?).
>
>
> thanks,
> Arek
>
>
>
Received on Sat Nov 30 2002 - 15:54:43 CST