I just create database.My machine is running Win2000,there are plenty of RAM (2 GB),and available physical RAM is 1,7 GB.I choose for Oracle SGA 1 GB.But,I realized Oracle choose 128 MB for physical RAM,and others in virtual memory.Now I have 1,6 GB physical memory free.
How one can say:Hey,Oracle,use physical memory!!!
Thanks a lot,i thought Oracle at startup allocate memory.......
Memory is allocated on-demand and "it's all virtual" and that's really the way you want it to be. You can rely upon the operating-system to minimize physical paging I/O as much as it possibly can. In your situation the computer may never page anything out at all. Even though DBMSes like Oracle are brimming with memory-management knobs of their own, I think it best that the host operating-system be left as the master of its own affairs. "Chips are cheap" now, although they weren't when those knobs were put in.