I am working on a data warehousing application. Currently, the machine has 4 CPUs. There is a plan to use the vPars feature of HP-UX 11i by sharing 2 CPUs for another application (a different instance). Could you please advise:
1) How will the CPU_COUNT parameter be affected with vPars?
2) Correct me if I'm wrong, as per my understanding with vPars, applications can share CPUs resources. If this is true, how will the Oracle instance know this? During Oracle instance start up, this value has already been taken by Oracle through the OS call.
3) What about memory sharing? If with vPars memory is also shared, then how will the memory dependent Oracle instance system parameters be affected?
You are correct. The CPU_COUNT parameter is computed when the instance starts. The point to remember here is that CPU_COUNT is used primarily in the computation of parallel query operations. So if the load increases on your machine, you can still use the vPars functionality to allocate more CPUs for Oracle to take advantage of (for shadow processes).
The same holds true for memory. Although you won't be able to enlarge your SGA, the additional memory can be used for sort area. If you know that you are going to be able to allocate more memory during peak usage, you can take this into account when sizing the SORT_AREA_SIZE parameter.