Re: "Correct" term for a 1:1 relationship between a "database" and an "instance" where > 1 such things are on the same physical server?
Date: Fri, 24 Jul 2009 12:58:49 -0700 (PDT)
Message-ID: <95e3526c-f413-411d-9059-48e4c1a4a293_at_o15g2000yqm.googlegroups.com>
On Jul 22, 10:29�am, ddf <orat..._at_msn.com> wrote:
> On Jul 22, 8:37�am, dana <dana_at_w..._at_yahoo.com> wrote:
>
> > Here's another question for you:
>
> > 1) Would there ever be any practical reason for two instances (procs +
> > SGA) to access the same database (collection of data treated as a
> > unit) on the same, unpartitioned physical server?
>
> > Dana
>
> > Dana
>
> That, I believe, is the basic definition of RAC -- two or more
> instances accessing a single database.
>
> David Fitzjarrell
But with RAC you would expect each instance to be running concurrently on different servers. While some Oracle 'experts' have managed to create a RAC setup with multiple instances on a single server the set up is non-standard, unsupported, and for demonstartion purposes only.
On a UNIX platform it used to be fairly easy to change the instance idenifier, SID, that was used to identify a running Oracle instance used to access a database. That is you could shut the instance down, make a few quick changes, and start a differently named instance then access the same database you were just working with from a different instance name. Only one instance can access a non-RAC database at a time. There was little practical application for this functionality.
HTH -- Mark D Powell -- Received on Fri Jul 24 2009 - 14:58:49 CDT