Re: Multiple instance with multiple version of Oracle

On Wed, 12 Feb 2003 13:53:16 +0000, Useko Netsumi wrote:

> Thank you Howards, it seems that I have to use the1st option(have 2
> instances running)
>
> Just to explain my reason, that I have a very limited resources(diskspace,
> memory, and an AMD box) . Diskspace I can add an external SCSI but I have
> limited memory.
>
> It would be nice if I can find a workaround to create both 9i and 8i
> database in the same box using one(1) instance only - so it does not take
> up more memory. I guess what I'm asking is that can oracle share SGA with
> different version of Oracle? Does it make any sense?
>
> Thanks again in advance.
>
> PS: Please forgive my lack of knowledge...
>

Nothing to forgive: we all had to start somewhere.

Now I see what you are after, I'm afraid the answer is a definite no. An Oracle SGA (as you put it... an 'Instance' = SGA+other things) can only ever manage one database. You want the one SGA to manage two databases simultaneously... that can never happen, not even in a cluster.

But be aware that whilst a database is permanent (stored on disk), the instance is purely temporary: you can shut it down or start it up at will. If this is a home computer and you want only to learn about Oracle, then there's nothing to say you have to have both instances running at the same time. Want to do some 8i work? Startup the 8i instance, and open the 8i database with it. Time to switch to 9i? Shutdown the 8i instance, change your ORACLE_SID, startup the 9i instance, open the 9i database.

Also bear in mind that an instance can be really quite small: I've got two running at the moment that are only 50MB or so each. You'll have to tune them that way, since the Oracle GUI tools you might use to create the databases seem to assume everyone has at least 500GB of RAM going spare! (I exaggerate slightly!!).

Finally, although the minimum recommended RAM for 9i is 512MB, you can install it with just 192MB (you might be able to take it even lower, but it failed when I tried 128MB). So if you are going to install 9i at all, I'd assume you have at least 192MB of RAM -and, with the installs safely out of the way, that should be sufficient to run two very small instances simultaneously purely for learning purposes (they'll be very slow, but they'll work). Received on Wed Feb 12 2003 - 13:05:39 CST