Re: Single vs Multiple instances on a server

"Ed" <esicl_at_aol.com> wrote in message
news:6c8bac75.0205010542.686685d0_at_posting.google.com...
> Hi,
>
> Could anyone elighten me on what the rationale would be for creating
> multiple Oracle instances on a (Unix) server (each containing
> different, small applications), as opposed to having a single instance
> with each application in its own schema.
>
> What are the disadvantages / advantages, resource-wise?
>
> Thanks

Multiple instance advantages

1. More flexibility for tuning. Can tune each instance differently.
2. More granular availability. If an instance goes down it only effects one application.

Single Instance Advantages

1. Easier administration. Only one instance to worry about.
2. Can have foreign keys accross schemas but not accross instances.
3. Will probably use less memory because there's only one set of instance processes running.

Regardless of which way you go may I make another suggestion? Resolve your connections through either LDAP or Oracle Names (deprecated in 9i), not with tnsnames, and have a separate alias for each application, even if they all point to the same instance. That way you can easily move an application to it's own server if you ever need to with minimal changes to the clients. Received on Wed May 01 2002 - 09:16:31 CDT