What To Do If the Binary SPFile Is Wrong for the Default Instance? - Oracle DBA FAQ - Introduction to Oracle Database 10g Express Edition

Let's say the SPFile for the default instance is a binary file, and some settings are wrong in the SPFile, like SGA setting is bellow 20MB, how do you change a setting in the binary file? This seems to be a hard task, because the binary SPFile is not allowed to be edited manually. It needs to be updated by the server with instance started. But you can not start the instance because the SPFile has a wrong setting.

One way to solve the problem is to stop using the binary SPFile, and use a text version of the a parameter file to start the instance. Here is an example of how to use the backup copy (text version) of the parameter file for the default instance to start the instance:

>.\bin\sqlplus
Enter user-name: SYSTEM/fyicenter AS SYSDBA
Connected to an idle instance

SQL> startup 
   PFILE=$ORACLE_HOME\config\scripts\initXETemp.ora;

ORACLE instance started.

Total System Global Area  146800640 bytes
Fixed Size                  1286220 bytes
Variable Size              58724276 bytes
Database Buffers           83886080 bytes
Redo Buffers                2904064 bytes
Database mounted.
Database opened.

As you can see, 10g XE is distributed with a backup copy of the parameter file for the default instance XE. The "startup" can take an option called PFILE to let you use a SPFILE from any location. The default instance is running correctly now.