About Oracle spfile 

The Oracle spfile is a binary representation of the text-based init.ora file. By default, a new Oracle9i database will be working on a pfile, so the spfile must be created from the pfile at the SQL prompt.

The spfile is created using the CREATE SPFILE statement; this requires connecting as SYSDBA.

Connect system/manager as sysdba;

CREATE SPFILE FROM PFILE;

This command creates an spfile in a non-default location ($ORACLE_HOME/database). However, you can fully-qualify the path name is the "create spfile" statement:

CREATE SPFILE='/u01/admin/prod/pfile/file_mydb.ora'

FROM

PFILE=/u01/admin/prod/pfile/initprod.ora';

Warning - After an spfile is created, when you bounce the database you may encounter an error. To get around this, you have to reconnect as SYSDBA and use the STARTUP command.

The addition of the spfile has changed the search path for the Oracle startup deck. Oracle9i now uses the following path:

   1:  Search for the spfile$ORACLE_SID.ora file in the default location,

   2:  Look for the spfile.ora; and

   3:  Search for the pfile by name init$ORACLE_SID.ora.

Once you have an spfile, you can change any initialization parameter with the "alter system" command. See using scope in Oracle parameter changes.