Re: Instance vs Schema pro/cons

Marc Eggenberger wrote:
>
> Hi there.
>
> I need some opinions ...
>
> Its about if its better to have one oracle instace and several
> applications in schemas or if I can be better to have several instances
> on one server.
>
> I would normally go the one instance / everything else in schemas way
> because of the overhead (having multiple sga's etc)
>
> Multiple instances are more independant. So if you need different
> settings (that are instance wide). Or maybe to seperate customers more.
>
> Do you have other pros and cons?

Step 1 is to refer to your Service Level Agreement, be it in writing or implied! Usrers and management have expectations, and it's up to us to translate those expectations into reality or into $.

In 8i/9i, Resource Manager can be used to provide resource prioritization and allocation by 'app' and/or 'app role'. However, AFAIK, it does not understand the total resource availability on the machine, just that which the instance is using.

IMO - pro for schema = ability to let Resource Manager do it's thing properly.

I generally think of instance as base unit of 'upgradeability' as well as 'optionality'. So if you have several apps that demand an independant upgrade cycle you might need to split along instance lines. Or if you need an option (Spatial, Partitioning, etc.) the licenses generally require match back to core DB licenses and I'd recommend 'this machine has Spatial ...'

Due to the overhead, I prefer one instance on one server and strongly advise use of multiple servers for multiple instances, rather than multiple instances for one server. Load management is hard enough as it is! Received on Wed Nov 26 2003 - 10:22:15 CST