I suppose those 4 processors and 4G of RAM are all on one system board so that configuring the hardware as two distinct domains is not an option. Other than purchasing more hardware, you may want to consider Sun's Solaris Resource Manager. Unfortunately, I have no experience with it so I cannot add anything to the marketing information. Maybe others can.

Meanwhile, make sure that you are using priority_paging so that intense demand for file system pages by one instance will not page out anonymous and executable pages from the other.

How do you manage the division of resources between 2 instances located on the same host?

We have two Oracle 8i instances (and a number of other applications) running on the same server. One in particular is drastically hogging the bulk of the server resources thus impeding the performance of the other instance and related applications

As far as memory conflicts go, we're running an ad hoc query system on one instance, which means it can get resource hungry and can only be tuned/designed to an extent. The issue is that the resources it can grab should be limited, so they don't eat into a minimum resource allocation that the other instance should get.

I am not aware of a way to use the DBMS_RESOURCE_MANAGER across two instances. Is there anything we can do here? I'm not sure how we specify how the two instances relate in terms of resources ... perhaps something in the init.ora file?

Our Oracle environment resides on an exclusive E10K domain with 4 dedicated (400mhz) processors, 4GB RAM.