Oracle provides two different types of mutually exclusive parameter files that you can use, PFILE and SPFILE. Let’s look at the PFILE in a bit more detail.

As we said, the parameters are stored in either a PFILE or an SPFILE. The PFILE is a text-based file, and the “init.ora” file has been around for over a decade. Inside the PFILE are a number of database settings called parameters. These parameters help the Oracle programs know how to start. The parameters tell the Oracle programs how much memory to allocate, where to put files related to the database and where certain database files already exist.

If you are using a PFILE, it takes on the form of initSID.ora, meaning the file will use the ORACLE_SID you defined when you created the database.  If your SID is called testdb, the resulting PFILE should be called inittestdb.ora

As the PFILE is text based, one can edit it in an editor like vi on UNIX or Notepad on Windows. When you have changed it, you need to make sure you save your changes to disk before you exit the editor. Also, make sure you save it as a plain text file, since some editors (like Microsoft Word) can save documents in special formats that Oracle would not be able to read.

Depending on which operating system you are running on, your PFILE is located by default in the ORACLE_HOME\database (usually the case on Windows) or ORACLE_HOME\dbs directory for most other platforms