Sanae BEKKAR – My Blog –

The Oracle developers simply rename the process as it is loaded into memory.

The name of the single Oracle process that is running right now (our dedicated server process; more on this later) is oracle $ORACLE_SID.

That naming convention makes it very easy to see what processes are associated with which instances and so on. So, let’s try to start the instance now:
SQL> startup

ORA-01078: failure in processing system parameters LRM-00109: could not open parameter file ‘/home/ora12cr1/app/ora12cr1/product/12.1.0/dbhome_1/dbs/ initora12c.ora’
Notice the error about a missing file named initora12c.ora.

That file, referred to colloquially as an init.ora file, or more properly as a parameter file, is the sole file that must exist to start up an instance—we need either a parameter file (a simple flat file that I’ll describe in more detail shortly) or a stored parameter file.

We’ll create the parameter file now and put into it the minimal information we need to actually start a database instance.

(Normally, we’d specify many more parameters, such as the database block size, control file locations, and so on).

By default, this file is located in the $ORACLE_HOME/dbs directory and has the name init${ORACLE_SID}.ora:

[ora12cr1@dellpe dbs]$ cd $ORACLE_HOME/dbs

[ora12cr1@dellpe dbs]$ echo db_name=ora12c > initora12c.ora

[ora12cr1@dellpe dbs]$ cat initora12c.ora db_name=ora12c

and then, once we get back into SQL*Plus:
[ora12cr1@dellpe dbs]$ sqlplus / as sysdba
SQL*Plus: Release 12.1.0.1.0 Production on Mon Sep 2 14:42:27 2013
Copyright (c) 1982, 2013, Oracle.  All rights reserved.
Connected to an idle instance.
SQL> startup nomount

ORACLE instance started.
Total System Global Area  329895936 bytes

Fixed Size                  2287960 bytes

Variable Size             272631464 bytes

DatabaseBuffers           50331648 bytes

Redo Buffers                4644864 bytes
We used the nomount option to the startup command since we don’t actually have a database to mount yet  (the SQL*Plus documentation includes all of the startup and shutdown options).