pfile and spfile - more to learn

I thought I was quite knowlegable about spfile/pfile, especially after reading Tom Kyte's book: Expert Oracle Database Architecure Chapter 3 Files. However, weeks ago, I saw a pfile that has only one line for one of our production databases. This puzzled me for a while. Today I decided to have a test.

The line looks similiar to:
spfile=/path/to/spfile/spfileSID.ora

I was told our VCS cluster software uses pfile to start up the db. I can not confirm if this is necessary. But most likely this is why the DBA creates such a pfile. And I don't know we can do this, this is the point - one can always learn something new about Oracle.

In my test environment (10.2.0), I have a spfile under this location:

vmlinux1:/app/oracle/product/10.2.0/db_1/dbs/temp [DBT10G] $ ls
spfileDBT10G.ora

I have a pfile at stardand default location and it has only one line to tell oracle where the spfile is.

vmlinux1:/app/oracle/product/10.2.0/db_1/dbs [DBT10G] $ cat initDBT10G.ora
spfile='/app/oracle/product/10.2.0/db_1/dbs/temp/spfileDBT10G.ora'


Now I start the DB with pfile:

vmlinux1:/app/oracle/product/10.2.0/db_1/dbs [DBT10G] $ sqlplus /nolog

SQL*Plus: Release 10.2.0.1.0 - Production on Tue Jul 21 14:40:49 2009

Copyright (c) 1982, 2005, Oracle. All rights reserved.

idle> conn / as sysdba
Connected to an idle instance.
idle> startup pfile='/app/oracle/product/10.2.0/db_1/dbs/initDBT10G.ora';
ORACLE instance started.

Total System Global Area 268435456 bytes
Fixed Size 1218920 bytes
Variable Size 92276376 bytes
Database Buffers 171966464 bytes
Redo Buffers 2973696 bytes
Database mounted.
Database opened.

When checking the parameter spfile, we can see the value is the full name of the spfile. So It looks like Oracle knows that it is started up with a spfile actually.

idle> show parameter spfile

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
spfile string /app/oracle/product/10.2.0/db_1/dbs/temp/spfileDBT10G.ora