I was wondering how many oracle instances can I have on a oracle NT server? In the event that I can have more than one oracle instance, is it possible to just rename/copy the control file I already have to a new ORACLE_SID name? How can I get a new control file for the new oracle instance?
You can have more than 1 instance on NT. No, you cannot use the controlfile of an existing db for another instance. You can use Database Assistant to create another instance. Specify the location of the controlfile in the init.ora for the new instance. When the db is created, it creates the controlfile in the the specified location.
I guess it's possible to have as many Instances as you have resources to run them... You can certainly have more than one (the most I've run on NT is about 5).
Unfortunately it's not just a case of renaming the control file!
You need to create services for each database first... Then assuming you want to use the same data from an existing database, you would either need to create a new database and import the data... or I guess you could use the existing database files in a new location, and create a new control file for this database (where you would then point it to the new datafiles location, and rename the database) - oh, and don't forget you need a different pfile for each database with the correct db_name in.
Post up what you're trying to do, and a little more about the databases (e.g. SGA size etc), and your machine details (RAM size mainly).