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Oracle® Database Administrator's Reference
11g Release 2 (11.2) for Linux and UNIX-Based Operating Systems

Part Number E10839-07
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1 Administering Oracle Database

This chapter provides information about administering Oracle Database on UNIX-based operating systems. It contains the following sections:

See Also:

The appropriate appendix in this guide for platform-specific information about administering Oracle Database

1.1 Overview

You must set Oracle Database environment variables, parameters, and user settings for Oracle Database to work. This chapter describes the various settings for Oracle Database.

In Oracle Database files and programs, a question mark (?) represents the value of the ORACLE_HOME environment variable. For example, Oracle Database expands the question mark in the following SQL statement to the full path of the Oracle home directory:

SQL> ALTER TABLESPACE TEMP ADD DATAFILE '?/dbs/temp02.dbf' SIZE 200M

Similarly, the at sign (@) represents the ORACLE_SID environment variable. For example, to indicate a file that belongs to the current instance, run the following command:

SQL> ALTER TABLESPACE tablespace_name ADD DATAFILE tempfile@.dbf

You can create a syslog audit trail to track administrative activities.

See Also:

"Using the Syslog Audit Trail to Audit System Administrators on UNIX Systems" in Oracle Database Security Guide for more information on audit trails.

1.2 Environment Variables

This section describes the most commonly used Oracle Database and operating system environment variables. You must define some environment variables before installing Oracle Database. This section covers the following topics:

To display the current value of an environment variable, use the env command. For example, to display the value of the ORACLE_SID environment variable, run the following command:

$ env | grep ORACLE_SID

To display the current value of all environment variables, run the env command as follows:

$ env | more

1.2.1 Oracle Database Environment Variables

Table 1-1 describes some environment variables used with Oracle Database.

Table 1-1 Oracle Database Environment Variables

Variable Detail Definition

NLS_LANG

Function

Specifies the language, territory, and character set of the client environment. The client character set specified by NLS_LANG must match the character set of the terminal or terminal emulator. If required, NLS_LANG can be temporarily reset to another character set before starting a non-interactive batch program to match the character set of files and scripts processed by this program. The character set specified by NLS_LANG can be different from the database character set, in which case the character set is automatically converted.

Refer to Oracle Database Globalization Support Guide for a list of values for this variable.

 

Syntax

language_territory.characterset

 

Example

french_france.we8iso8859p15

ORA_NLS10

Function

Specifies the directory where the language, territory, character set, and linguistic definition files are stored.

 

Syntax

directory_path

 

Example

$ORACLE_HOME/nls/data

ORA_TZFILE

Function

Specifies the full path and file name of the time zone file. The Oracle Database Server always uses the large time zone file ($ORACLE_HOME/oracore/zoneinfo/timezlrg_number.dat). If you want to use the small time zone file on the client side, you must set this environment variable to the full path of the small time zone file ($ORACLE_HOME/oracore/zoneinfo/timezone_number.dat). If you use the small time zone file on the client side, you must ensure that the database you access contains data only in the time zone regions recognized by the small time zone file.

 

Syntax

directory_path

 

Example

$ORACLE_HOME/oracore/zoneinfo/timezlrg_11.dat

ORACLE_BASE

Function

Specifies the base of the Oracle directory structure for Optimal Flexible Architecture compliant installations.

 

Syntax

directory_path

 

Example

/u01/app/oracle

ORACLE_HOME

Function

Specifies the directory containing the Oracle software.

 

Syntax

directory_path

 

Example

$ORACLE_BASE/product/11.2.0/dbhome_1

ORACLE_PATH

Function

Specifies the search path for files used by Oracle applications such as SQL*Plus. If the full path to the file is not specified, or if the file is not in the current directory, then the Oracle application uses ORACLE_PATH to locate the file.

 

Syntax

Colon-separated list of directories:

directory1:directory2:directory3
 

Example

/u01/app/oracle/product/11.2.0/dbhome_1/bin:.

Note: The period adds the current working directory to the search path.

ORACLE_SID

Function

Specifies the Oracle system identifier.

 

Syntax

A string of numbers and letters that must begin with a letter. Oracle recommends a maximum of 8 characters for system identifiers. For more information about this environment variable, refer to Oracle Database Installation Guide.

 

Example

SAL1

ORACLE_TRACE

Function

Enables the tracing of shell scripts during an installation. If it is set to T, then many Oracle shell scripts use the set -x command, which prints commands and their arguments as they are run. If it is set to any other value, or no value, then the scripts do not use the set -x command.

 

Syntax

T or not T

 

Example

T

ORAENV_ASK

Function

Controls whether the oraenv or coraenv script prompts or does not prompt for the value of the ORACLE_SID environment variable. If it is set to NO, then the scripts do not prompt for the value of the ORACLE_SID environment variable. If it is set to any other value, or no value, then the scripts prompt for a value for the ORACLE_SID environment variable.

 

Syntax

NO or not NO

 

Example

NO

SQLPATH

Function

Specifies the directory or list of directories that SQL*Plus searches for a login.sql file.

 

Syntax

Colon-separated list of directories: directory1:directory2:directory3

 

Example

/home:/home/oracle:/u01/oracle

TNS_ADMIN

Function

Specifies the directory containing the Oracle Net Services configuration files.

 

Syntax

directory_path

 

Example

$ORACLE_HOME/network/admin

TWO_TASK

Function

Specifies the default connect identifier to use in the connect string. If this environment variable is set, then do not specify the connect identifier in the connect string. For example, if the TWO_TASK environment variable is set to sales, then you can connect to a database by using the following command:

SQL> CONNECT USERNAME
Enter password: password
 

Syntax

Any connect identifier.

 

Range of Values

Any valid connect identifier that can be resolved by using a naming method, such as a tnsnames.ora file or a directory server.

 

Example

PRODDB_TCP

NLS_OS_CHARSET

Function

Specifies the Oracle character set name corresponding to the UNIX locale character set in which the file names and user names are encoded by the operating system. You must set the environment variable NLS_OS_CHARSET, if the UNIX locale character set is different from the Oracle client character set. These two character sets may differ, for example, if NLS_LANG is set to a particular character set used to encode an SQL script, which is to be executed in an SQL*Plus session. Usually, the Oracle client character set and the operating system character set are the same and NLS_OS_CHARSET must not be set.

 

Syntax

characterset

 

Example

WE8ISO8859P1


Note:

To prevent conflicts, do not define environment variables with names that are identical to the names of Oracle Database server processes, for example ARCH, PMON, and DBWR.

1.2.2 UNIX Environment Variables

Table 1-2 describes UNIX environment variables used with Oracle Database.

Table 1-2 Environment Variables Used with Oracle Database

Variable Detail Definition

ADA_PATH (AIX only)

Function

Specifies the directory containing the Ada compiler.sm

 

Syntax

directory_path

 

Example

/usr/lpp/powerada

ORA_FPU_PRECISION (Linux x86 only)

Function

For all precompiled applications where calculations are done using the extended precision of the x86 Floating Point Unit, this variable must be set to EXTENDED before running the application.

Note: Setting this variable results in non-IEEE compliant floating point results. Hence, ORA_FPU_PRECISION should not be set if you are using either BINARY_FLOAT or BINARY_DOUBLE datatypes, documented as note 246916.1 in My Oracle Support (formerly OracleMetaLink) Web site:

https://support.oracle.com

CLASSPATH

Function

Used with Java applications. The required setting for this variable depends on the Java application. Refer to the product documentation for Java application for more information.

 

Syntax

Colon-separated list of directories or files: directory1:directory2:file1:file2

 

Example

There is no default setting. CLASSPATH must include the following directories:

$ORACLE_HOME/JRE/lib:$ORACLE_HOME/jlib

DISPLAY

Function

Used by X-based tools. Specifies the display device used for input and output. Refer to the X Window System documentation for information.

 

Syntax

hostname:server[.screen]

where hostname is the system name (either IP address or alias), server is the sequential code number for the server, and screen is the sequential code number for the screen. If you use a single monitor, then use the value 0 for both server and screen (0.0).

Note: If you use a single monitor, then screen is optional.

 

Example

135.287.222.12:0.0
bambi:0
 

Syntax

Colon-separated list of directories: directory1:directory2:directory3

 

Example

/usr/lib:$ORACLE_HOME/lib

HOME

Function

The home directory of the user.

 

Syntax

directory_path

 

Example

/home/oracle

LANG or LC_ALL

Function

Specifies the language and character set used by the operating system for messages and other output. Oracle tools that are programmed in Java, such as Oracle Universal Installer and Oracle Database Configuration Assistant, may also use this variable to determine the language of their user interface. Refer to the operating system documentation for more information.

LD_OPTIONS

Function

Specifies the default linker options. Refer to the ld man page for more information about this environment variable.

LPDEST (Solaris only)

Function

Specifies the name of the default printer.

 

Syntax

string

 

Example

docprinter

LD_LIBRARY_PATH

Function

Environment variable to specify the path used to search for libraries on UNIX and Linux. The environment variable may have a different name on some operating systems, such as LIBPATH on AIX, and SHLIB_PATH on HP-UX.

 

Syntax

Colon-separated list of directories: directory1:directory2:directory3

 

Example

/usr/dt/lib:$ORACLE_HOME/lib

PATH

Function

Used by the shell to locate executable programs; must include the $ORACLE_HOME/bin directory.

 

Syntax

Colon-separated list of directories: directory1:directory2:directory3

 

Example

/bin:/usr/bin:/usr/local/bin:/usr/bin/X11:$ORACLE_HOME/bin: $HOME/bin:.

Note: The period adds the current working directory to the search path.

PRINTER

Function

Specifies the name of the default printer.

 

Syntax

string

 

Example

docprinter

TEMP, TMP, and TMPDIR

Function

Specifies the default directories for temporary files; if set, tools that create temporary files create them in one of these directories.

 

Syntax

directory_path

 

Example

/u02/oracle/tmp


1.2.3 Setting a Common Environment

This section describes how to set a common operating system environment by using the oraenv or coraenv scripts, depending on the default shell:

  • For the Bourne, Bash, or Korn shell, use the oraenv command.

  • For the C shell, use the coraenv command.

oraenv and coraenv Script Files

The oraenv and coraenv scripts are created during installation. These scripts set environment variables based on the contents of the oratab file and provide:

  • A central means of updating all user accounts with database changes

  • A mechanism for switching between databases specified in the oratab file

You may find yourself frequently adding and removing databases from the development system or your users may be switching between several different Oracle Databases installed on the same system. You can use the oraenv or coraenv script to ensure that user accounts are updated and to switch between databases.

Note:

Do not call the oraenv or coraenv script from the Oracle software owner (typically, oracle) user's shell startup script. Because these scripts prompt for values, they can prevent the dbstart script from starting a database automatically when the system starts.

The oraenv or coraenv script is usually called from the user's shell startup file (for example, .profile or.login). It sets the ORACLE_SID and ORACLE_HOME environment variables and includes the $ORACLE_HOME/bin directory in the PATH environment variable setting. When switching between databases, users can run the oraenv or coraenv script to set these environment variables.

Note:

To run one of these scripts, use the appropriate command:
  • coraenv script:

    % source /usr/local/bin/coraenv
    
  • oraenv script:

    $ . /usr/local/bin/oraenv
    

Local bin Directory

The directory that contains the oraenv, coraenv, and dbhome scripts is called the local bin directory. All database users must have read access to this directory. Include the path of the local bin directory PATH environment variable setting for the users. When you run the root.sh script after installation, the script prompts you for the path of the local bin directory and automatically copies the oraenv, coraenv, and dbhome scripts to the directory that you specify. The default local bin directory is /usr/local/bin. If you do not run the root.sh script, then you can manually copy the oraenv or coraenv and dbhome scripts from the $ORACLE_HOME/bin directory to the local bin directory.

1.2.4 Setting the System Time Zone

The TZ environment variable sets the time zone. It enables you to adjust the clock for daylight saving time changes or different time zones.

See Also:

Oracle Database Globalization Support Guide and Oracle Database Administrator's Guide for more information about setting the database time zone

1.3 Initialization Parameters

The following sections provide information about Oracle Database initialization parameters:

1.3.1 DB_BLOCK_SIZE Initialization Parameter

The DB_BLOCK_SIZE initialization parameter specifies the standard block size for the database. This block size is used for the SYSTEM tablespace and by default in other tablespaces.

The maximum value to which you can set the DB_BLOCK_SIZE is 16 KB on Linux x86. It is 32 KB on other platforms.

Note:

You cannot change the value of the DB_BLOCK_SIZE initialization parameter after you create a database.

1.3.2 ASM_DISKSTRING Initialization Parameter

Note:

Only Automatic Storage Management instances support the ASM_DISKSTRING initialization parameter.

The syntax for assigning a value to the ASM_DISKSTRING initialization parameter is as follows:

ASM_DISKSTRING = 'path1'[,'path2', . . .]

In this syntax, pathn is the path to a raw device. You can use wildcard characters when specifying the path.

Table 1-3 lists the platform-specific default values for the ASM_DISKSTRING initialization parameter.

Table 1-3 Default Values of the ASM_DISKSTRING Initialization Parameter

Platform Default Search String

AIX

/dev/rhdisk*

HP-UX

/dev/rdisk/*

Solaris

/dev/rdsk/*

Linux

/dev/raw/*


1.3.3 LOG_ARCHIVE_DEST_n Initialization Parameter

The maximum value that you can set for ASYNC in the LOG_ARCHIVE_DEST_n initialization parameter differs on UNIX platforms as listed in the following table:

Platform Maximum Value
HP-UX 51200
Other operating systems 102400

1.3.4 DISK_ASYNCH_IO Initialization Parameter (HP-UX)

The DISK_ASYNCH_IO initialization parameter determines whether the database files reside on raw disks or file systems. Asynchronous I/O is available only with Automatic Storage Management disk group which uses raw partitions as the storage option for database files. The DISK_ASYNCH_IO parameter can be set to TRUE or FALSE depending on where the files reside. By default, the value is set to TRUE.

Note:

The DISK_ASYNCH_IO parameter must be set to FALSE when the database files reside on file system. This parameter must be set to TRUE only when the database files reside on raw partitions.

1.4 Operating System Accounts and Groups

This section describes the following special operating system accounts and groups that are required by Oracle Database:

1.4.1 Creating Additional Operating System Accounts

If required, create additional operating system accounts. Users must be members of the OSDBA or OSOPER groups to connect to the database with administrator privileges.

1.4.2 Configuring the Accounts of Oracle Users

Update the startup files of the oracle user and the operating system accounts of Oracle users, specifying the appropriate environment variables in the environment file.

For the Bourne, Bash, or Korn shell, add the environment variables to the .profile file, or the .bash_profile file for the Bash shell on Red Hat Enterprise Linux.

For the C shell, add the environment variables to the .login file.

Note:

You can use the oraenv or coraenv script to ensure that Oracle user accounts are updated.

1.5 Using Trace Files

This section describes the trace (or dump) that Oracle Database creates to help you diagnose and resolve operating problems.

Each server and background process writes to a trace file. When a process detects an internal error, it writes information about the error to its trace file. The file name format of a trace file is sid_processname_unixpid.trc, where:

The following is a sample trace file name:

$ORACLE_BASE/diag/rdbms/mydb/mydb/trace/test_lgwr_1237.trc

Set the MAX_DUMP_FILE initialization parameter to at least 5000, to ensure that the trace file is large enough to store error information.