Oracle® Database Administrator's Reference 10g Release 2 (10.2) for UNIX-Based Operating Systems Part Number B15658-05 |
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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 DatabaseYou 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 belonging to the current instance, run the following command:
SQL> ALTER TABLESPACE tablespace_name ADD DATAFILE tempfile@.dbf
This section describes the most commonly used Oracle Database and operating system environment variables. You must define some of these environment variables before installing Oracle Database.
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
Table 1-1 describes the environment variables used with Oracle Database.
Table 1-1 Oracle Database Environment Variables
Note:
To prevent conflicts, do not define environment variables with names that are identical to the names of Oracle Database server processes, for exampleARCH
, PMON
, and DBWR
.Table 1-2 describes UNIX environment variables used with Oracle Database.
Table 1-2 Environment Variables Used with Oracle Database
Variable | Detail | Definition |
---|---|---|
|
Function |
|
|
Syntax |
|
|
Example |
|
Function |
Used with Java applications. The required setting for this variable depends on the Java application. Refer to the product documentation for your Java application for more information. |
|
|
Syntax |
Colon-separated list of directories or files: |
|
Example |
There is no default setting.
|
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 Note: If you use a single monitor, then |
|
Example |
135.287.222.12:0.0 bambi:0 |
Function |
Specifies the list of directories that the shared library loader searches to locate shared object libraries at run time. See the |
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|
Syntax |
Colon-separated list of directories: |
|
Example |
|
Function |
The home directory of the user. |
|
|
Syntax |
|
|
Example |
|
Function |
Specifies the language and character set used by the operating system for messages and other output. Refer to the operating system documentation for more information. Note: This environment variable is not used on Apple Mac OS X. |
|
Function |
Specifies the default linker options. Refer to the |
|
Function |
Specifies the name of the default printer. |
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|
Syntax |
|
|
Example |
|
Function |
Specifies the list of directories that the shared library loader searches to locate shared object libraries at run time. Refer to the On HP-UX, specifies the path for 64-bit shared libraries. |
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|
Syntax |
Colon-separated list of directories: |
|
Example |
|
|
Function |
Specifies the list of directories that the shared library loader searches to locate specific 64-bit shared object libraries at run time. Refer to the |
|
Syntax |
Colon separated list of directories: |
|
Example |
|
Function |
Specifies the list of directories that the shared library loader searches to locate shared object libraries at run time. Refer to the |
|
|
Syntax |
Colon-separated list of directories: |
|
Example |
|
Function |
Used by the shell to locate executable programs; must include the |
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|
Syntax |
Colon-separated list of directories: |
|
Example |
Note: The period adds the current working directory to the search path. |
Function |
Specifies the name of the default printer. |
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|
Syntax |
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Example |
|
Function |
Specifies the list of directories that the shared library loader searches to locate shared object libraries at run time. Refer to the |
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Syntax |
Colon-separated list of directories: |
|
Example |
|
Function |
Specifies the default directories for temporary files; if set, tools that create temporary files create them in one of these directories. |
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Syntax |
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Example |
|
Function |
Specifies a file containing X Window System resource definitions. Refer to the X Window System documentation for more information. |
This section describes how to set a common operating system environment by using the oraenv
or coraenv
scripts, depending on your 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 your 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 theoraenv
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
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.
The TZ
environment variable sets the time zone. It enables you to adjust the clock for daylight saving time changes or different time zones. The adjusted time is used to time-stamp files, produce the output of the date
command, and obtain the current value of SYSDATE
.
Oracle recommends that you do not change your personal TZ value. Using different values of TZ, such as GMT+24, may change the date a transaction is recorded. This changed date affects Oracle applications that use SYSDATE. To avoid this problem, use sequence numbers to order a table instead of date columns.
The following sections provide information about Oracle Database initialization parameters:
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, Mac, and Solaris. It is 32 KB on AIX, HP-UX, and Tru64 UNIX.
Note:
You cannot change the value of theDB_BLOCK_SIZE
initialization parameter after you create a database.Note:
Only Automatic Storage Management instances support theASM_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 |
|
HP-UX |
|
Linux |
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Mac OS X |
|
Solaris |
|
Tru64 UNIX |
|
See Also:
Theglob(7)
man page for platform-specific information about the wildcard character patterns that you can use when specifying the path of a raw deviceThe 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 |
---|---|
zSeries Linux | 12800 |
HP-UX and Tru64 UNIX | 51200 |
Other operating systems | 102400 |
This section describes the following special operating system accounts and groups that are required by Oracle Database:
The Oracle software owner account, usually named oracle
, is the account that you use to install the Oracle software. You can use different Oracle software owner accounts to install the software in separate Oracle home directories. However, for each Oracle home directory, you must use the same account that installed the software for all subsequent maintenance tasks on that Oracle home directory.
Oracle recommends that the Oracle software owner have the Oracle Inventory group as its primary group and the OSDBA group as its secondary group.
Table 1-4 describes the special operating system groups required by Oracle Database.
Table 1-4 Operating System Groups
Group | Typical Name | Description |
---|---|---|
OSDBA |
|
Operating system accounts that are members of the OSDBA group have special database privileges. Members of this group can connect to the database using the SYSDBA privilege. The Oracle software owner is the only required member of this group. You can add other accounts as required. |
OSOPER |
|
The OSOPER group is an optional group. Operating system accounts that are members of the OSOPER group have special database privileges. Members of this group can connect to the database using the SYSOPER privilege. |
Oracle Inventory |
|
All users installing Oracle software must belong to the same operating system group. This group is called the Oracle Inventory group. It must be the primary group of the Oracle software owner during installations. After the installation, this group owns all the Oracle files installed on the system. |
See Also:
Oracle Database Administrator's Guide and Oracle Database Installation Guide for more information about the OSDBA group and SYSDBA privileges, and the OSOPER group and SYSOPER privilegesOracle Database uses several features of the UNIX operating system to provide a secure environment for users. These features include file ownership, group accounts, and the ability of a program to change its user ID during processing.
The two-task architecture of Oracle Database improves security by dividing work (and address space) between the user program and the oracle
program. All database access is achieved through the shadow process and special authorizations in the oracle
program.
See Also:
Oracle Database Administrator's Guide for more information about security issuesOracle programs are divided into two sets for security purposes: those that can be run by all (other
in UNIX terms), and those that can be run by DBAs only. Oracle recommends that you take the following approach to security:
The primary group for the oracle
account must be the oinstall
group.
The oracle
account must have the dba
group as a secondary group.
Although any user account that requires the SYSDBA privilege can belong to the dba
group, the only user accounts that should belong to the oinstall
group are the Oracle software owner accounts. For example, the oracle
user.
If you choose to use external authentication, then you must use the value of the OS_AUTHENT_PREFIX
initialization parameter as a prefix for Oracle user names. If you do not explicitly set this parameter, then the default value on UNIX is ops$
, which is case-sensitive.
To use the same user names for both operating system and Oracle authentication, set this initialization parameter to a null string:
OS_AUTHENT_PREFIX=""
See Also:
Oracle Database Administrator's Guide for more information about external authenticationYou can use a password file to identify users that can use the SYSDBA and SYSOPER privileges when connecting to the database. If you use Oracle Database Configuration Assistant to create a database, then the assistant creates a password file for the new database. If you create the database manually, then create the password file for it as follows:
Log in as the Oracle software owner.
Use the orapwd
utility to create the password file as follows:
$ $ORACLE_HOME/bin/orapwd file=filename password=password entries=max_users
The following table describes the values that you must specify in this command.
Value | Description |
---|---|
filename |
The name of the file in which password information is written
The name of the file must be |
password |
The password for the SYS user
If you use an ALTER USER statement to change the password for the SYS user after you connect to the database, then both the password stored in the data dictionary and the password stored in the password file are updated. This parameter is mandatory. |
max_users |
Sets the maximum number of entries permitted in the password file. This is the maximum number of distinct users permitted to connect to the database simultaneously with either the SYSDBA or the SYSOPER privilege. |
See Also:
Oracle Database Administrator's Guide for more information about using theorapwd
utilityWhen using Oracle Database Configuration Assistant to create a database, users must change the SYS and SYSTEM account passwords. You cannot use the default CHANGE_ON_INSTALL and MANAGER passwords.
For security reasons, Oracle Database Configuration Assistant locks most Oracle user accounts after it creates the database. It does not lock the SYS or SYSTEM accounts. You must unlock any locked accounts and change their passwords before using them. To do this, you can use one of the following methods:
To change the passwords by using Oracle Database Configuration Assistant, click Password Management in the Database Configuration Assistant Summary window.
Alternatively, use SQL*Plus to connect to the database as SYS and run the following command to unlock an account and reset its password:
SQL> ALTER USER username IDENTIFIED BY passwd ACCOUNT UNLOCK;
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.
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 and Mac.
For the C shell, add the environment variables to the .login
file.
Note:
You can use theoraenv
or coraenv
script to ensure that Oracle user accounts are updated.The following sections provide information about using raw devices (raw partitions or raw volumes):
See Also:
The appendix corresponding to your platform in this guide for additional raw device tuning informationRaw devices (raw partitions or raw volumes) have the following potential disadvantages:
Raw devices may not solve problems with file size writing limits.
To display current file size limits, run one of the following commands:
Bourne, Bash, or Korn shell:
$ ulimit -a
C shell:
% limit
If a particular disk drive has intense I/O activity and performance would benefit from movement of an Oracle data file to another drive, then it is likely that no acceptably sized partition or volume exists on a drive with less I/O activity. It may not be possible to move files to other disk drives if you are using raw devices.
Raw devices are more difficult to administer than data files stored on a file system or in an Automatic Storage Management disk group.
Consider the following issues when deciding to use raw devices:
Raw disk partition availability
Use raw partitions for Oracle files only if you have at least as many raw disk partitions as Oracle data files. If disk space is a consideration and the raw disk partitions are already created, then match data file size to partition size as closely as possible to avoid wasting space.
You must also consider the performance implications of using all the disk space on a few disks as opposed to using less space on more disks.
Logical volume manager
Logical volume managers manage disk space at a logical level and hide some of the complexity of raw devices. With logical volumes, you can create logical disks based on raw partition availability. The logical volume manager controls fixed-disk resources by:
Mapping data between logical and physical storage
Enabling data to span multiple disks and to be discontiguous, replicated, and dynamically expanded
For RAC, you can use logical volumes for drives associated with a single system, as well as those that can be shared with more than one system of a cluster. Shared drives enables all files associated with a RAC database to be placed on these shared logical volumes.
Dynamic performance tuning
To optimize disk performance, you can move files from disk drives with high activity to disk drives with low activity. Most hardware vendors who provide the logical disk facility also provide a graphical user interface (GUI) that you can use for tuning.
Mirroring and online disk replacement
You can mirror logical volumes to protect against loss of data. If one copy of a mirror fails, then dynamic resynchronization is possible. Some vendors also provide the ability to replace drives online in conjunction with the mirroring facility.
When creating raw devices, ensure that:
The owner is the Oracle software owner user (oracle
) and the group is the OSDBA group (dba
).
The size of an Oracle data file created in a raw partition is at least two Oracle block sizes smaller than the size of the raw partition.
See Also:
The operating system documentation for more information about creating raw devicesOn AIX and Tru64 UNIX systems, data files on raw logical volumes may have offsets for the first block of the Oracle data. This offset is required by the logical volume manager.
You can use the $ORACLE_HOME/bin/offset
utility to determine the offset value. You may need to do this, for example, if you want to transfer the data file to a different device.
See Also:
Appendix A for more information about creating a raw logical volume on AIX, which enables you to use a zero offset. The zero offset is recommended for raw logical volumes on AIX.You can use both raw character devices and block devices as raw volumes in creating a database. Because block devices are supported, the kernel level limitation on the maximum number of raw devices is removed and you can configure additional raw volumes to meet your requirements.
This section describes the trace (or dump) and alert files that Oracle Database creates to help you diagnose and resolve operating problems. It includes the following sections:
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:
sid
is the instance system identifier
processname
is a three or four-character abbreviated process name identifying the Oracle Database process that generated the file (for example, pmon
, dbwr
, ora
, or reco
)
unixpid
is the operating system process ID number
The following is a sample trace file name:
$ORACLE_BASE/admin/TEST/bdump/test_lgwr_1237.trc
All trace files for background processes are written to the destination directory specified by the BACKGROUND_DUMP_DEST
initialization parameter. If you do not set this initialization parameter, then the default directory is $ORACLE_HOME/rdbms/log
.
All trace files for user processes are written to the destination directory specified by the USER_DUMP_DEST
initialization parameter. If you do not set this initialization parameter, then the default directory is $ORACLE_HOME/rdbms/log
. Set the MAX_DUMP_FILE
initialization parameter to at least 5000 to ensure that the trace file is large enough to store error information.
The alert_
sid
.log
file stores information about significant database events and messages. Events that affect the database instance or database are recorded in this file. This file is associated with a database and is located in the directory specified by the BACKGROUND_DUMP_DEST
initialization parameter. If you do not set this initialization parameter, then the default directory is $ORACLE_HOME/rdbms/log
.