Re: Maximum Oracle instances on a Server? - Databases reside on servers.

Mark wrote:

> We run separate servers for DSS and OLTP, with multiple instances on
> each server (up to 15) with multiple applications (schemas) per
> instance( 5 - 10). We are running on Sun 4500's with multiple CPU's
> and SAN storage.
>
> This configuration has worked well in the past but recently we have
> run into situations where we needed to do "emergency maintenance" on
> one of the schemas to restore the schema to the state before the users
> truncated the production tables thinking they waer test data. The
> application, from a vendor not home grown, has the test and production
> data in separate schemas but the application allows users to switch
> between prod and test at will.) We could not get the approval of the
> other application owners to take down the instance for the repairs. So
> the first group had to wait. This would not have been an issue if the
> application was in its own instance.
>
> This event (along with a number of others) has resulted in a project
> to determine the resource requirements to move all applications into
> their own instances. We may be looking at nearly 200 instances by the
> time we are through.
>

"This would not have been an issue if the application was in its own instance."

Really, a schema resides in a database.
An instance is a set of processes and memory structures that a user application can connect to. The schemas are collections of objects that reside in tablespaces - stored in datafiles - that are persistent across startup/shutdown. If the application resided entirely in global temporary tables, then maybe it could be thought of as being in an instance, as after shutdown it would no longer exist.

How could you repair an instance if it were shutdown? How can you repair something that does not exist? Yes, you could restore and perform media recovery on one or more tablespaces while the instance was running, but the commands are "alter database ..." not "alter instance".

If you run OPS (or RAC) - you have multiple instances accessing a single database. Won't the terminology get very confusing in a hurry?

Oracle Server software would be such a much more pleasant subject in general if people would get the terminology down. The application resides in a database.

Paul Received on Wed Feb 27 2002 - 01:43:27 CST