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Lesson 2 Oracle database configuration file
Objective What is the init.ora file.

Oracle documentation

Most Oracle documentation and those of us who write about Oracle make a very common assumption about the init.ora file. We assume that when we refer to init.ora it is understood that this file may be named something else. I performed a default installation of Oracle8 on my NT platform. I took the default instance name of orc1 during the install. Oracle installed a file called initseed.ora on my disk and created a file called initorc1.ora that is specific to the instance orc1. Both files are located in my c:\oracel8\database subdirectory. For convenience, we will refer to init.ora as a general name rather than an instance specific name.

init.ora file

Question: What is the purpose and function of the init.ora file in Oracle?
The init.ora file, also known as the initialization parameter file, is a crucial component of Oracle database systems. It serves as the primary configuration file for an Oracle instance and contains a set of parameters that determine the behavior, performance, and resource allocation for the instance. The init.ora file is read during the startup process of an Oracle database and its settings directly influence the overall functioning of the database system.
Purpose and Function of the init.ora File:
  1. Instance Configuration: The init.ora file dictates the configuration of an Oracle instance, which is a combination of the System Global Area (SGA) and Oracle background processes. The SGA is a shared memory area that contains data and control information essential for the database system, whereas the background processes manage I/O, data consistency, and other critical tasks.
  2. Resource Allocation: The init.ora file contains parameters that determine the allocation of memory and other system resources for the Oracle instance. This includes settings related to the buffer cache, shared pool, and large pool, among others. Adjusting these parameters can help optimize the performance of the database system.
  3. Database Behavior: Parameters in the init.ora file influence various aspects of database behavior, such as the degree of parallelism, the optimizer mode, and the default locking mechanism. By modifying these parameters, administrators can fine-tune the performance and behavior of their Oracle databases.
  4. Backup and Recovery: The init.ora file also contains settings related to database backup and recovery, including parameters that control the frequency and location of archived redo logs. These settings are crucial for maintaining data integrity and ensuring the recoverability of the database system in case of a failure.
  5. Diagnostic and Monitoring: Parameters within the init.ora file can be configured to enable or disable diagnostic and monitoring features, such as the Automatic Workload Repository (AWR) and Automatic Database Diagnostic Monitor (ADDM). These features help database administrators identify performance bottlenecks and recommend solutions to optimize database performance.

In summary, the init.ora file is a vital element in the configuration and management of Oracle database systems. It governs various aspects of instance behavior, resource allocation, and database performance, allowing administrators to customize their Oracle instances according to specific requirements. Careful management and understanding of the init.ora file can lead to optimized database performance and efficient resource utilization.
The init.ora file contains initialization information about your database and instance. There are over 130 parameters that can be set in your init.ora file by using Oracle Instance Manager, Oracle Server Manager, or any text editor. All modifications specified in the init.ora file will take effect the next time you start up your instance. Most parameters are set with default values by the instance and do not concern our backup and recovery plan, but there are some parameters that you may want to set manually.

When you consider the number of database options (Java, objects, parallel server, and so on) and potential platforms (Unix, NT, Netware, LINUX, MVS, and so on) it is easy to understand why there are more than 130 parameters. This module introduces certain parameters that relate to backup and recovery. In the wrap up lesson, a sidebar will accumulate the parameters that were covered.
While it isn't the only place to find information about your database, the init.ora file should be one of the first places you look to determine how your database is set up. View the slide show below to see parameter information using three different tools, init.ora, Server manager, and the Oracle Enterprise Manager tools.

Parameter Settings Example
These tools are the three primary ways of viewing parameters. Notice that the information is presented a little differently with each tool. The next lesson is about the database control file.