When an Oracle instance starts, it reads initialization parameters from an initialization
parameter file. This file can be either a read-only text file, or a read/write binary file.
The binary file is called a server parameter file, and it always resides on the server. A
server parameter file enables you to change initialization parameters with ALTER
SYSTEM commands and to persist the changes across a shutdown and startup. It also
provides a basis for self-tuning by the Oracle Database server. For these reasons, it is
recommended that you use a server parameter file. You can create one from your
edited text initialization file or by using the Database Configuration Assistant.

Before you create a server parameter file, you can start an instance with a text
initialization parameter file. Upon startup, the Oracle instance first searches for a
server parameter file in a default location, and if it does not find one, searches for a
text initialization parameter file. You can also override an existing server parameter
file by naming a text initialization parameter file as an argument of the STARTUP
command .

Default file names and locations for the text initialization parameter file are shown in
the following table:

Platform Default Name Default Location
UNIX and Linux init$ORACLE_SID.ora $ORACLE_HOME/dbs
Windows init%ORACLE_SID%.ora %ORACLE_HOME%database

参数化参数文件
1. 使用spfile
2. Windows下默认的位置和名称为%ORACLE_HOME%database : init%ORACLE_SID%.ora