12
Initial Configuration

Initial configuration implies that database attributes and parameters must be formed prior to building the desired database. However, that is not necessarily the easiest method to use.

When you use Oracle Expert to help configure a new database, you should allow the Oracle Server to create a default instantiation of the database and then build upon that implementation. By allowing a default database to be created, you enable Oracle Expert to acquire automatically much of the needed information regarding your database.

This chapter describes the following:

• Advantages of Using Oracle Expert
• Configuring a New Database
• User-Provided Information
• Oracle Expert Recommendations

Advantages of Using Oracle Expert

When you use Oracle Expert for initial configuration tuning, Oracle Expert can provide more appropriate instance parameters for the database you are creating than the Oracle Server default instance parameters. Oracle Expert takes the following data into account before recommending instance parameters for the database you are creating:

• system data

  Includes memory and CPU data, plus the operating system page size.

• Database class data

  Includes the version of the database, specified options, and database user, tablespace, and public synonym data.

• Oracle Expert instance parameter default values

  You can view the default value for each instance parameter and decide whether to let Oracle Expert calculate an appropriate value for the instance parameter value or use a value that you assign.

• control parameter values

  Includes data about the type of workload (OLTP, DSS, or batch) that runs against the database, your tolerance for unscheduled downtime, and other control parameter values.

Oracle Expert analyzes all this data before providing instance parameter recommendations for a database you are creating. Oracle Expert makes better recommendations when provided with complete and accurate system, Database class, and control parameters data.

Configuring a New Database

Create a default database as you would if you were installing the Oracle Server. Then tune this default database iteratively as more data about the database becomes available. Oracle Expert analyzes this additional data provided after the initial configuration of the database to produce improved tuning and design recommendations.

Performing Initial Configuration for a Database

Perform the following steps:

1. In the tree list, click on the default database you created and click the Tuning Session folder under that database name.
2. Create a new tuning session by choosing File=>Create.
   1. To change the default name of the tuning session, click on the default name and type in the new name.
   2. On the Scope page, select all the instance tuning categories. Do not select the application and structure tuning categories.
   3. In the Control Parameter section of the Scope page, set the value of the "Initial configuration tuning" control parameter to Enabled.
3. On the View/Edit page of the tuning session window, do the following:
   1. Click on the System folder. Choose Edit=>Add. For the Name attribute, type in the name of the system where the instance will run. Supply the most accurate values you can for the memory, CPU, and operating page size parameters. Click the OK button to save the values you added.
   2. Click on the new system icon. Choose Edit=>Modify. On the Rules page, supply the most accurate value you can for the "Default concurrent sessions" rule.
   3. Click on the Database object, choose Edit=>Modify and enter the values for the attributes that do not contain values.
   4. Click on the Instance object, choose Edit=>Modify and enter the name of the system object you just created for the instance's System attribute. Also, enter values for attributes that do not contain values. Click the OK button to save the values you added.
4. On the Analyze page of the tuning session window, do the following:
   1. Click the View Control Parameters button, then choose the class of workload (for example, OLTP, DSS, batch) you expect to run against the database. Adjust the other control parameters according to the type of database you want.
   2. Click the Perform Analysis button. Oracle Expert evaluates the system, instance, database, and control parameters to determine appropriate settings for the INIT.ORA file.
5. On the Implement page of the tuning session window, click the Generate Files button to create the INIT.ORA file.
6. Update your database, using the Oracle Expert INIT.ORA file to configure the instance.

Improving the Initial Configuration of the Database

Once you have performed the initial configuration of your new database, improve on the initial configuration by performing the following steps:

1. After the database is up and running, provide Oracle Expert with schema and workload data.
2. Collect instance statistics while requests from a representative workload are accessing the database. The instance tuning recommendations Oracle Expert generates from the instance statistics gathered while the instance is in use will be better than the initial instance tuning recommendations.

Now that the instance has been tuned, Oracle Expert will be able to provide you with good results when you perform application tuning and structure tuning.

Viewing and Changing Default Instance Parameters for a Database Not Yet Created

Oracle Expert allows you to view and change the default instance parameter values it uses for configuring a database. To view and modify default values for instance parameters, do the following:

1. During the initial configuration tuning session, select the View/Edit page of the tuning session window.
2. Select the type of instance parameter (for example, SGA, parallel query, sort, I/O, or other) for which you want to see the default values.
3. Choose Edit=>Modify. On the Rules page of the Edit dialog box, you can view the default value for a particular instance parameter.

   To find the default value for an instance parameter, locate the rule whose name is the control parameter name preceded by the word "Default" and examine the default value in the rule's Value column. For example, to view the default value for the log_buffer SGA parameter, find the rule named "Default log_buffer" and view the default value (32768) in the Value column.

   You can change the default value for an instance parameter in two ways. One way is to provide a new default value for the instance parameter in the Value column of the default rule (the rule preceded by the word "Default"). When you use this method of specifying a default value for a rule, Oracle Expert considers system data, Database class data, and other control parameter values before generating instance parameter recommendations, and may recommend that you use a different value than the one you chose for the instance parameter.

   A second method allows you to provide a new default value for an instance parameter that Oracle Expert will not override. To do this, find the override rule and provide the default value you want Oracle Expert to use for the instance parameter. The name of the override rule for a particular instance parameter is the parameter name with the words "parameter override" appended. For example, the override rule for the log_buffer parameter is called "log_buffer parameter override." When you use the override rule to provide a new default value for an instance parameter, Oracle Expert uses the value you provide for that instance parameter when it generates instance tuning recommendations, and it will not recommend that you provide a new value for that instance parameter.

User-Provided Information

Providing accurate information about the following aspects of your database helps Oracle Expert generate a good initial configuration:

• default concurrent sessions (system rules)
• amount of CPU and memory available for database use (system attributes)
• hardware information, such as total memory (system attributes)
• control parameters

If you cannot provide an exact value for some of these items, you can specify a range of values using control parameters, and Oracle Expert will use this data to make configuration recommendations. In some cases, Oracle Expert can make good initial configuration recommendations for part of your database even when you are unable to provide all the previously mentioned information.

Oracle Expert Recommendations

When you select tuning categories for the instance, application, and structure tuning types, Oracle Expert makes recommendations such as:

• initial SGA parameter settings for the instance
• how to optimize parallel query operations for the instance
• how to optimize sort operations for the instance
• how Oracle segments should be separated into different tablespaces
• the storage parameters for Oracle segments
• the columns for which an index should be created in tables

---