Re: 3GB RAM usage by Oracle

DGK wrote:

> Hello,
>
> I have the following configuration:
>
> O/S: W2K
> RAM: 3GB
> Pagefile: 4GB
> Oracle version: 8.1.7
> SGA: 1,290,397,724
> Current usage of RAM: 1.5GB
>
> Since this server is dedicated only to Oracle database, I want it to
> utilise the full available RAM of 3GB.

Please read the archives at Google on this sort of issue.

The question you have to ask is: WHY?

Why do you feel compelled to let Oracle have all your RAM (and don't you think the O/S would like some too?).

If your database is tuned, then it doesn't need the extra RAM. If it is not tuned, then tune it properly. And that, pace a well-known author, does NOT mean throw every byte of spare RAM at the SGA you happen to have available. It means: work out whether it actually *needs* extra memory. If you can justify it, then fine (but you won't get it past 2GB of SGA on that platform and with that specification). But *justify* it first.

> I tried to increase the sga size by
> by changing the DB_BLOCK_BUFFERS. But during database startup, I receive
> the following messages;
>
> ORA-27101 shared memory realm does not exist and ORA-27102 out of memory.
>
> Could anybody help me to solve this problem?

First, don't do what you're doing. Not until you can justify, with cold, hard numbers, that it needs doing, anyway. And I'll lay small odds that you can't.

Second, IF you can justify it with some proper tracing and diagnostics, then visit http://www.pontis.biz/resources/articles/oracle_on_windows.php for a lesson on how to do it. But with only 3GB of RAM available to you, you're not going to be able to increase your SGA that much.

Third. Don't do what you're doing.

Fourth. Oracle's own advice is: never use more than 50% of the available physical RAM on a server. Ideally, not more than about 1/3rd -but 50% if pushed. So with only 3GB of RAM, your SGA is already a little too big. If you push it up to 2GB plus, you will likely induce extra O/S paging. Things will slow down as a result.

Fifth. Did I mention not doing what you're doing?

Regards
HJR
>
> thanks,
> GK
Received on Mon Aug 23 2004 - 01:19:41 CDT