Re: What Is An Oracle Instance, Really ?

A copy of this was sent to Jannette <jannetteyiu_at_my-deja.com> (if that email address didn't require changing) On Sat, 25 Dec 1999 21:15:20 GMT, you wrote:

>Pls educate me...I've read MANY explanations. But none of them seems to
>be in the context of reality.
>So if I have 4 running databases (4 service names) on one server with a
>single Oracle Home and a single
>Oracle80.exe, does that mean I have 4 Instances running ? ie is each
>database mapped to a one and one only Instance ?
>

instance = set of oracle processes running and an SGA database = set of files (control, redo, data, init)

a single database may be mounted by many instances (Oracle Parallel Server does this. >1 computer mounts a single database allowing for many instances to have read/write access to the same set of files from many computers).

an instance mounts at most 1 database at a time.

In your case, it sounds like you have 4 instances and 4 databases. Each instance mounts and opens an individual database...

>Thanks
>
>Jannette
>
>
>Sent via Deja.com http://www.deja.com/
>Before you buy.

--
See http://osi.oracle.com/~tkyte/ for my columns 'Digging-in to Oracle8i'... Current article is "Part I of V, Autonomous Transactions" updated June 21'st  

Thomas Kyte                   tkyte_at_us.oracle.com
Oracle Service Industries     Reston, VA   USA

Opinions are mine and do not necessarily reflect those of Oracle Corporation Received on Sat Dec 25 1999 - 17:40:58 CST