Each new release of Oracle requires changes to Oracle's initialization files. This is especially true in Oracle when you are using Oracle Parallel Server (OPS) and Shared Server.This lesson describes the initialization parameters of the Oracle8i database that are needed to support new features of Net. Look at the SlideShow below to read about several important parameters. The SlideShow shows you the initialization parameters as you see them in the Enterprise Manager's Instance Manager. Each page highlights a different parameter.
When the Oracle database is started, one of the first things it needs to do is read the database initialization parameter file. The parameter file (init.ora) is created by the DBA and defines the overall instance configuration, such as how much memory should be allocated to the instance, the file locations, and internal optimization parameters.
Here is a sample init.ora file:
db_cache_size = 176000M
db_2k_cache_size = 2048M
db_16k_cache_size = 99000M
db_keep_cache_size = 600000M
db_recycle_cache_size = 64000M
shared_pool_size = 14000M
In this section we will look at the database parameter file in more detail.
First we will look at the two different types of parameter files you can use,
- PFILE's and
followed by a look at the parameters that are maintained in the database parameter file. Finally, we will look at how to manage the initialization parameter file.
The initialization parameters
are a very important part of the Oracle database. Oracle reads the initialization parameter values from either a PFILE or SPFILE as the database is starting. The parameters tell the Oracle programs
- how much memory to allocate,
- where to put files related to the database and
- the location of existing datafiles.
A parameter has a name and a value. In this example, we have a parameter named db_block_size. This parameter tells oracle how big each individual block in the database is.In this case, each block is 8192 bytes, or 8k, in size.
The next parameter you see is the
This parameter defines the location of Oracle trace files (log files) that are created by the Oracle background processes (we talked about the Oracle processes earlier in this book) and the important alert log where database messages reside. In this case, all files written by Oracle background processes will be in the /u01/oracle/admin/mydb/bdump directory.
Some parameters are dynamic and they can be changed while the database is running.
For example, you can decrease the database buffer cache
in many cases while the database instance is running with the alter system command:
alter system set db_recovery_file_dest_size=10g;
In this example, we dynamically changed the
to a value of 10 gigabytes (10g). The database will maintain this parameter until it is rebooted, unless a SPFILE is used.
These parameters are stored in the init.ora file. You can modify this file directly, or you can use the Enterprise Manager's Instance Manager to modify the file.
The next lesson shows you how to configure Net using the Net Assistant.