Oracle initialization file not a Database File

The initialization file is also often called a parameter file. It is a text file containing a number of parameter settings that affect how the Oracle processes operate when you start an instance and open a database. In that sense, the initialization file is more related to an Oracle instance than to a database. However, one of the most important parameters in the initialization file points to the database control files. For the most part, opening your database is not dependent on having one specific set of parameters. It is not unheard of for a site to have two initialization files, both used with the same database but for different purposes. One may be optimized for use during the day when most of the workload comes from small, interactive transactions. The other may be optimized for use at night, when the work comes from large, batch processes.

Since the initialization file is read when an Oracle instance is started, changes to these parameters do not take effect until an instance is stopped and restarted. Remember, though, that turning on automatic archiving does not put the database in ARCHIVELOG mode. Similarly, placing the database in ARCHIVELOG mode does not enable the automatic archiving process. You should also make sure that the archive log destination has enough room for the logs Oracle will automatically write to it. If the archive logfile destination is full, Oracle will hang since it cannot archive additional redo logfiles.
The archived redo logs are critical for database recovery. Just as you can duplex the online redo logs, you can also specify multiple archive log destinations. Oracle will copy filled redo logs to specified destinations and you can also specify whether all copies must succeed or not.
The initialization parameters for this functionality are as follows:

LOG_ARCHIVE_DUPLEX_DEST

Specifies an additional location for redundant redo logs.

LOG_ARCHIVE_MIN_SUCCEED_DEST

Indicates whether the redo log must be successfully written to one or all of the locations. Valid values are 1 through 10 if multiplexing and 1 or 2 if duplexing. See your Oracle documentation for the additional parameters and views that enable and control this functionality.

Initialization parameters are configuration parameters that affect the basic operation of an instance. The instance reads initialization parameters from a file at startup. Oracle Database provides many initialization parameters to optimize its operation in diverse environments. Only a few of these parameters must be explicitly set because the default values are usually adequate.

Most initialization parameters belong to one of the following functional groups:

1. Parameters that name entities such as files or directories
2. Parameters that set limits for a process, database resource, or the database itself
3. Parameters that affect capacity, such as the size of the SGA (these parameters are called variable parameters)

Variable parameters are of particular interest to database administrators because they can use these parameters to improve database performance.

Initialization parameters are divided into two groups:

1. basic and
2. advanced.

Typically, you must set and tune only the approximately 30 basic parameters to obtain reasonable performance. The basic parameters set characteristics such as the database name, locations of the control files, database block size, and undo tablespace. In rare situations, modification to the advanced parameters may be required for optimal performance. The advanced parameters enable expert DBAs to adapt the behavior of the Oracle Database to meet unique requirements. Oracle Database provides values in the starter initialization parameter file provided with your database software, or as created for you by the Database Configuration Assistant.
You can edit these Oracle-supplied initialization parameters and add others, depending on your configuration and how you plan to tune the database. For relevant initialization parameters not included in the parameter file, Oracle Database supplies defaults.