Understand the initialization parameter file of oracle10g

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Understand the initialization parameter file of oracle10g
When an oracle instance is started, it reads the initialization parameters from an initialization parameter file. This initialization parameter file can be a read-only text file or a binary file that can be read/written. This binary file is called a server parameter file, which is always stored on the server. By using the server parameter file, the administrator can save the changes made to the database by using the alter system command, even if the database is restarted, the changes will not be lost. Therefore, Oracle recommends that you use the server parameter file. You can use edited text initialization files or DBCA to create server parameter files.
Before you create a server parameter file, you can use the text initialization parameter file to start the database. When the database is started, the ORACLE instance first searches for the server parameter file in the default location. If not, it searches for the text initialization parameter file. You can also use the STARTUP command to specify a text file to start the database. In this case, the server parameter file does not work.

Default initialization parameter file name and default path
Default platform name default path
Windows init % ORACLE_SID %. ora % ORACLE_HOME % \ database

Initialize the parameter file template (unix platform)
Control_files = (/u0d/lcg03/control.001.dbf,
/U0d/lcg03/control.002.dbf,
/U0d/lcg03/control.003.dbf)
Db_name = lcg03
Db_domain = us.oracle.com
Log_archive_dest_1 =
"LOCATION =/net/fstlcg03/private/yaliu/testlog/log. lc1_3.fstlcg03/lcg03/arch"
Log_archive_dest_state_1 = enable
DB _ block_size = 8192
Pga_aggregate_target = 2500 M
Processes = 1000
Sessions = 1200
Open_cursors = 1024
Undo_management = AUTO
Shared_servers = 3
Remote_listener = tnsfstlcg03
Undo_tablespace = smu_nd1
Compatible = 10.2.0
Sga_target = 1500 M
Nls_language = AMERICAN
Nls_territory = AMERICA
Db_recovery_file_dest =
/Net/fstlcg03/private/yaliu/testlog/log. lc1_3.fstlcg03/lcg03/arch
Db_recovery_file_dest_size = 100G

Oracle Database provides a commonly used initialization parameter template. You can use this template or use dbca to create your own initialization parameter file. You can edit the template parameter file according to your database needs, modify or add your own parameter values. oracle uses the default value for parameters that do not appear in the file.
If you create an oracle database for the first time, we recommend that you do not change the initialization parameters too much for oracle. After you are familiar with the database and computer environment, you can use the alter system command to dynamically adjust many initialization parameters. If you use the text initialization parameter file, your changes will only affect the current instance, and the value set in the text initialization parameter file will be restored after the restart. To make the change permanently valid, you must also manually update the value in the text initialization parameter file. If you use the server parameter file, the alter system command can affect the current instance and update the server initialization file at the same time, so that the change is permanently valid.
The following describes some basic initialization parameters:
Determine the global database name
Specify a quick Recovery Area)
Control File
Database block sizes)
Manage the global zone of the system
Maximum number of processes
Manage the rollback Space
Compatibility initialization parameters and incompatible functions that cannot be canceled
Set License Parameters
Determine the global database name
The global database name contains the user-specified local database name and network address of the database. The DB_NAME initialization parameter determines the local name, And DB_DOMAIN specifies the network address. These two addresses constitute a unique name for the database on the network.
For example, to create a database named test.us.acme.com, the parameter value is as follows:
DB_NAME = test
DB_DOMAIN = us.acme.com
You can use the alter database rename GLOBAL_NAME command to RENAME the global DATABASE name. However, after db_name and db_domain are changed for the first time, you must restart the database and create a new control file.
DB_NAME initialization parameters
DB_NAME must be a text string of no more than eight characters. During database creation, database values stored in DB_NAME are recorded in data files, redo log files, and control files. If the DB_NAME value in the parameter file is inconsistent with the value saved in the control file when the database instance is started, the database cannot be started.
DB_DOMAIN initialization parameters
DB_DOMAIN indicates the text escape of the network address where the database is located. It is usually the domain name of the organization that owns the database. If the database you want to build is part of the distributed database system, be sure to wait for this parameter with caution.
Specified quick recovery zone
The quick recovery zone is the region where oracle can store and manage data recovery files. It is different from the database region. The database region refers to the directory where oracle manages the current database files (including data files, control File, redo logs now)
You can use the following initialization parameters to specify the quick recovery region.
DB_RECOVERY_FILE_DEST: Location of the quick recovery zone. It can be a directory, a file system, or an automatic storage management hard disk group (ASM ). It cannot be a raw file system)
In the RAC (Real Application Clusters) environment, this location must be on the cluster file system, the ASM hard disk group, or the shared directory created through NFS.
DB_RECOVERY_FILE_DEST_SIZE: specifies the maximum number of bytes that can be used in the quick recovery zone. This parameter must be specified before the DB_RECOVERY_FILE_DEST parameter is applied.
In the RAC environment, the two parameter values must be set with the same value in all instances.
If you have set the values of LOG_ARCHIVE_DEST and LOG_ARCHIVE_DUPLEX_DEST, the parameter values mentioned above will not work. You must disable LOG_ARCHIVE_DEST and LOG_ARCHIVE_DUPLEX_DEST before setting the quick recovery zone. As an alternative, you can configure the value of LOG_ARCHIVE_DEST_n. If you have not set the value of LOG_ARCHIVE_DEST_n for the local machine, LOG_ARCHIVE_DEST_10 will be set as the quick recovery zone when you set the quick recovery zone.
We recommend that you use the quick recovery area in Oracle to simplify recovery.

Control File
The CONTROL_FILES parameter specifies one or more control files. When you create a database, the Control Files specified in this parameter are created.
If this parameter is not set, oracle will create a control file for you, or if you enable oracle_managed files, it will create a control file managed by oracle.
If you want the database to create another file as a backup when creating the control file, the file list specified in the CONTROL_FILES parameter cannot contain existing files in the system. If you want to re-use an existing file or overwrite an existing file, you must set the re-use option (warning, if you choose to re-use the option, the content in the existing file will be overwritten)
Oracle strongly recommends that each database use at least two control files stored on different physical hard disks.
Database block size
The DB_BLOCK_SIZE initialization parameter specifies the standard data block size. This block size is used for SYSTEM tablespaces and is also used for other tablespaces by default. Oracle databases support up to four additional non-standard block sizes.
DB_BLOCK_SIZE
The standard block size should be set to the most common value. In many cases, you only need to set this parameter. For example, 4 k or 8 k. If you do not set this parameter, the default size is determined by the operating system. This is usually enough.
This parameter value cannot be changed after the database is created, unless the database is re-created. If the size of the database block is different from that of the operating system, make sure that the size of the database block is a multiple of the size of the operating system block. For example, if the operating system block size is 2 k (2048 bytes), the following parameter values are valid.
DB _ block_size = 4096
Larger block sizes provide more effective I/O operations. Therefore, if the following conditions are true, it is best to specify a database block larger than the operating system block size.
1. Databases have ultra-large memory and ultra-fast hard disks on large-scale computer systems. For example, large hosts have huge hardware resources, and generally set 4 K or larger blocks.
2. The block size of the operating system is too small. For example, if the database uses such a small block, the database will be busy with a lot of I/O operations.
Non-standard block size
When creating a new tablespace, you can specify a non-standard block size (different from the block size of the system tablespace ). The block size can use any 2-level encrypted value, such as 2 k, 4 k, 8 k, 16 k, and 32 k. The minimum value varies depending on the operating system. Therefore, the preceding value cannot be used in some systems.
To use non-standard blocks, you must configure the cache for different non-standard blocks in SGA. The configuration method will be described later.

This non-standard block feature is particularly useful in Mobile databases. For example, you can transfer a 4 K tablespace from an OLAP environment to a data warehouse with 8 K as the standard block size.

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