Re: Multiple Instances - when do you use them?

In article <19991203231445.25725.00000458_at_ng-fx1.aol.com>,   drodrigu1_at_aol.com (DRODRIGU1) wrote:
> Could anyone tell me why would I need more than one instance on a
database?
> Is this to increase the number of users? Thanks.
>
> DR
>

The primary reason to use OPS, Oracle Parallel Server, to allow multiple instances with access to one physical database is for redunantcy. If the system must be accessible with the absolute minimum of unplanned down time. If your application was reaching the maximum hardware limitations for your vendor of choice product line then you may need it to support a larger user base or application work load.

OPS works pretty well if you can partition your application such that all updaters come from one machine for specific tables. Generally you would want to group these tables together into files/tablespaces that then are accessed from only one instance, at least for update. This reduces the cross instance contention to the files and prevents certain performance and locking issues that can be problems in an OPS environment.

Cross instance updates are supported by the base product. It is just that the system will probably function much better if it can be partitioned.

If you are considering using OPS, which we have used with good luck since '94 or '95, then you should really give serious consideration to paying for expert advise from consultants with actual experience. You want someone who has actually supported an OPS environment, not someone who has installed one and left.
--
Mark D. Powell -- The only advice that counts is the advice that  you follow so follow your own advice --

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Before you buy. Received on Sat Dec 04 1999 - 13:17:44 CST