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Oracle® Database Administrator's Guide 10g Release 2 (10.2) Part Number B14231-01 |
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# 1 Overview of Administering an Oracle Database

This chapter presents an overview of the environment and tasks of an Oracle Database administrator (DBA). It also discusses DBA security and how you obtain the necessary administrative privileges.

The following topics are discussed:

- Types of Oracle Database Users

- Tasks of a Database Administrator

- Selecting an Instance with Environment Variables

- Identifying Your Oracle Database Software Release

- Database Administrator Security and Privileges

- Database Administrator Authentication

- Creating and Maintaining a Password File

- Server Manageability

## Types of Oracle Database Users

The types of users and their roles and responsibilities depend on the database site. A small site can have one database administrator who administers the database for application developers and users. A very large site can find it necessary to divide the duties of a database administrator among several people and among several areas of specialization.

This section contains the following topics:

- Database Administrators

- Security Officers

- Network Administrators

- Application Developers

- Application Administrators

- Database Users

### Database Administrators

Each database requires at least one database administrator (DBA). An Oracle Database system can be large and can have many users. Therefore, database administration is sometimes not a one-person job, but a job for a group of DBAs who share responsibility.

A database administrator's responsibilities can include the following tasks:

- Installing and upgrading the Oracle Database server and application tools

- Allocating system storage and planning future storage requirements for the database system

- Creating primary database storage structures (tablespaces) after application developers have designed an application

- Creating primary objects (tables, views, indexes) once application developers have designed an application

- Modifying the database structure, as necessary, from information given by application developers

- Enrolling users and maintaining system security

- Ensuring compliance with Oracle license agreements

- Controlling and monitoring user access to the database

- Monitoring and optimizing the performance of the database

- Planning for backup and recovery of database information

- Maintaining archived data on tape

- Backing up and restoring the database

- Contacting Oracle for technical support

### Security Officers

In some cases, a site assigns one or more security officers to a database. A security officer enrolls users, controls and monitors user access to the database, and maintains system security. As a DBA, you might not be responsible for these duties if your site has a separate security officer. Please refer to Oracle Database Security Guide for information about the duties of security officers.

### Network Administrators

Some sites have one or more network administrators. A network administrator, for example, administers Oracle networking products, such as Oracle Net Services. Please refer to Oracle Database Net Services Administrator's Guide for information about the duties of network administrators.

See Also: Part VII, "Distributed Database Management", for information on network administration in a distributed environment

### Application Developers

Application developers design and implement database applications. Their responsibilities include the following tasks:

- Designing and developing the database application

- Designing the database structure for an application

- Estimating storage requirements for an application

- Specifying modifications of the database structure for an application

- Relaying this information to a database administrator

- Tuning the application during development

- Establishing security measures for an application during development

Application developers can perform some of these tasks in collaboration with DBAs. Please refer to Oracle Database Application Developer's Guide - Fundamentals for information about application development tasks.

### Application Administrators

An Oracle Database site can assign one or more application administrators to administer a particular application. Each application can have its own administrator.

### Database Users

Database users interact with the database through applications or utilities. A typical user's responsibilities include the following tasks:

- Entering, modifying, and deleting data, where permitted

- Generating reports from the data

## Tasks of a Database Administrator

The following tasks present a prioritized approach for designing, implementing, and maintaining an Oracle Database:

Task 1: Evaluate the Database Server Hardware

Task 2: Install the Oracle Database Software

Task 3: Plan the Database

Task 4: Create and Open the Database

Task 5: Back Up the Database

Task 6: Enroll System Users

Task 7: Implement the Database Design

Task 8: Back Up the Fully Functional Database

Task 9: Tune Database Performance

Task 10: Download and Install Patches

Task 11: Roll Out to Additional Hosts

These tasks are discussed in the sections that follow.

Note: When upgrading to a new release, back up your existing production environment, both software and database, before installation. For information on preserving your existing production database, see Oracle Database Upgrade Guide.

### Task 1: Evaluate the Database Server Hardware

Evaluate how Oracle Database and its applications can best use the available computer resources. This evaluation should reveal the following information:

- How many disk drives are available to the Oracle products

- How many, if any, dedicated tape drives are available to Oracle products

- How much memory is available to the instances of Oracle Database you will run (see your system configuration documentation)

### Task 2: Install the Oracle Database Software

As the database administrator, you install the Oracle Database server software and any front-end tools and database applications that access the database. In some distributed processing installations, the database is controlled by a central computer (database server) and the database tools and applications are executed on remote computers (clients). In this case, you must also install the Oracle Net components necessary to connect the remote machines to the computer that executes Oracle Database.

For more information on what software to install, see "Identifying Your Oracle Database Software Release".

See Also: For specific requirements and instructions for installation, refer to the following documentation: The Oracle documentation specific to your operating system The installation guides for your front-end tools and Oracle Net drivers

### Task 3: Plan the Database

As the database administrator, you must plan:

- The logical storage structure of the database

- The overall database design

- A backup strategy for the database

It is important to plan how the logical storage structure of the database will affect system performance and various database management operations. For example, before creating any tablespaces for your database, you should know how many datafiles will make up the tablespace, what type of information will be stored in each tablespace, and on which disk drives the datafiles will be physically stored. When planning the overall logical storage of the database structure, take into account the effects that this structure will have when the database is actually created and running. Consider how the logical storage structure of the database will affect:

- The performance of the computer executing running Oracle Database

- The performance of the database during data access operations

- The efficiency of backup and recovery procedures for the database

Plan the relational design of the database objects and the storage characteristics for each of these objects. By planning the relationship between each object and its physical storage before creating it, you can directly affect the performance of the database as a unit. Be sure to plan for the growth of the database.

In distributed database environments, this planning stage is extremely important. The physical location of frequently accessed data dramatically affects application performance.

During the planning stage, develop a backup strategy for the database. You can alter the logical storage structure or design of the database to improve backup efficiency.

It is beyond the scope of this book to discuss relational and distributed database design. If you are not familiar with such design issues, please refer to accepted industry-standard documentation.

Part II, "Oracle Database Structure and Storage", and Part IV, "Schema Objects", provide specific information on creating logical storage structures, objects, and integrity constraints for your database.

### Task 4: Create and Open the Database

After you complete the database design, you can create the database and open it for normal use. You can create a database at installation time, using the Database Configuration Assistant, or you can supply your own scripts for creating a database.

Please refer to Chapter 2, "Creating an Oracle Database", for information on creating a database and Chapter 3, "Starting Up and Shutting Down" for guidance in starting up the database.

### Task 5: Back Up the Database

After you create the database structure, carry out the backup strategy you planned for the database. Create any additional redo log files, take the first full database backup (online or offline), and schedule future database backups at regular intervals.

See Also: Oracle Database Backup and Recovery Basics Oracle Database Backup and Recovery Advanced User's Guide

### Task 6: Enroll System Users

After you back up the database structure, you can enroll the users of the database in accordance with your Oracle license agreement, and grant appropriate privileges and roles to these users. Please refer to Chapter 22, "Managing Users and Securing the Database" for guidance in this task.

### Task 7: Implement the Database Design

After you create and start the database, and enroll the system users, you can implement the planned logical structure database by creating all necessary tablespaces. When you have finished creating tablespaces, you can create the database objects.

Part II, "Oracle Database Structure and Storage" and Part IV, "Schema Objects" provide information on creating logical storage structures and objects for your database.

### Task 8: Back Up the Fully Functional Database

When the database is fully implemented, again back up the database. In addition to regularly scheduled backups, you should always back up your database immediately after implementing changes to the database structure.

### Task 9: Tune Database Performance

Optimizing the performance of the database is one of your ongoing responsibilities as a DBA. Oracle Database provides a database resource management feature that helps you to control the allocation of resources among various user groups. The database resource manager is described in Chapter 24, "Using the Database Resource Manager".

See Also: Oracle Database Performance Tuning Guide for information about tuning your database and applications

### Task 10: Download and In stall Patches

After installation and on a regular basis, download and install patches. Patches are available as single interim patches and as patchsets (or patch releases). Interim patches address individual software bugs and may or may not be needed at your installation. Patch releases are collections of bug fixes that are applicable for all customers. Patch releases have release numbers. For example, if you installed Oracle Database 10.2.0.0, the first patch release will have a release number of 10.2.0.1.

See Also: Oracle Database Installation Guide for your platform for instructions on downloading and installing patches.

### Task 11: Roll Out to A dditional Hosts

After you have an Oracle Database installation properly configured, tuned, patched, and tested, you may want to roll that exact installation out to other hosts. Reasons to do this include the following:

- You have multiple production database systems.

- You want to create development and test systems that are identical to your production system.

Instead of installing, tuning, and patching on each additional host, you can clone your tested Oracle Database installation to other hosts, saving time and eliminating inconsistencies. There are two types of cloning available to you:

- Cloning an Oracle home—Just the configured and patched binaries from the Oracle home directory and subdirectories are copied to the destination host and "fixed" to match the new environment. You can then start an instance with this cloned home and create a database.

  You can use the Enterprise Manager Clone Oracle Home tool to clone an Oracle home to one or more destination hosts. You can also manually clone an Oracle home using a set of provided scripts and Oracle Universal Installer.

- Cloning a database—The tuned database, including database files, initialization parameters, and so on, are cloned to an existing Oracle home (possibly a cloned home).

  You can use the Enterprise Manager Clone Database tool to clone an Oracle database instance to an existing Oracle home.

See Also: Oracle Universal Installer and OPatch User's Guide and Enterprise Manager online help for details on how to clone an Oracle home. Enterprise Manager online help for instructions for cloning a database.

## Selecting an Instance wit h Environment Variables

Before you attempt to use SQL*Plus to connect locally to an Oracle instance, you must ensure that environment variables are set properly. When multiple database instances exist on one server, or when an Automatic Storage Management (ASM) instance exists on the same server as one or more database instances, the environment variables determine which instance SQL*Plus connects to. (This is also true when there is only one Oracle instance on a server.)

For example, each Oracle instance (database or ASM) has a unique system identifier (SID). To connect to an instance, you must at a minimum set the `ORACLE_SID` environment variable to the SID of that instance. Depending on the operating system, you may need to set other environment variables to properly change from one instance to another.

Refer to the Oracle Database Installation Guide or administration guide for your operating system for details on environment variables and for information on switching instances.

Note: This discussion applies only when you make a local connection—that is, when you initiate a SQL*Plus connection from the same machine on which the target instance resides, without specifying an Oracle Net Services connect identifier. When you make a connection through Oracle Net Services, either with SQL*Plus on the local or a remote machine, or with Enterprise Manager, the environment is automatically set for you. For more information on connect identifiers, see Oracle Database Net Services Administrator's Guide.

Solaris Example

The following Solaris example sets the environment variables that are required for selecting an instance. When switching between instances with different Oracle homes, the `ORACLE_HOME` environment variable must be changed.

    % setenv ORACLE_SID SAL1
    % setenv ORACLE_HOME /u01/app/oracle/product/10.1.0/db_1
    % setenv LD_LIBRARY_PATH /usr/lib:/usr/dt/lib:/usr/openwin/lib:/usr/ccs/lib

Most UNIX installations come with two scripts, `oraenv` and `coraenv`, that can be used to easily set these environment variables. For more information, see Administrator's Reference for UNIX Systems.

Windows Example

On Windows, you must set only the ORACLE_SID environment variable to select an instance before starting SQL*Plus.

    SET ORACLE_SID=SAL1

## Identifying Your Oracle Database Software Release

Because Oracle Database continues to evolve and can require maintenance, Oracle periodically produces new releases. Not all customers initially subscribe to a new release or require specific maintenance for their existing release. As a result, multiple releases of the product exist simultaneously.

As many as five numbers may be required to fully identify a release. The significance of these numbers is discussed in the sections that follow.

### Release Number Format

To understand the release nomenclature used by Oracle, examine the following example of an Oracle Database server labeled "Release 10.1.0.1.0".

Figure 1-1 Example of an Oracle Database Release Number

Description of the illustration admin002.gif

Note: Starting with release 9.2, maintenance releases of Oracle Database are denoted by a change to the second digit of a release number. In previous releases, the third digit indicated a particular maintenance release.

#### Major Database Release Number

The first digit is the most general identifier. It represents a major new version of the software that contains significant new functionality.

#### Database Maintenance Release Number

The second digit represents a maintenance release level. Some new features may also be included.

#### Application Server Release Number

The third digit reflects the release level of the Oracle Application Server (OracleAS).

#### Component-Specific Release Number

The fourth digit identifies a release level specific to a component. Different components can have different numbers in this position depending upon, for example, component patch sets or interim releases.

#### Platform-Specific Release Number

The fifth digit identifies a platform-specific release. Usually this is a patch set. When different platforms require the equivalent patch set, this digit will be the same across the affected platforms.

### Checking Your Current Release Number

To identify the release of Oracle Database that is currently installed and to see the release levels of other database components you are using, query the data dictionary view `PRODUCT_COMPONENT_VERSION`. A sample query follows. (You can also query the `V$VERSION` view to see component-level information.) Other product release levels may increment independent of the database server.

    COL PRODUCT FORMAT A35
    COL VERSION FORMAT A15
    COL STATUS FORMAT A15
    SELECT * FROM PRODUCT_COMPONENT_VERSION;

    PRODUCT                                  VERSION     STATUS
    ---------------------------------------- ----------- -----------
    NLSRTL                                   10.2.0.1.0  Production
    Oracle Database 10g Enterprise Edition   10.2.0.1.0  Prod
    PL/SQL                                   10.2.0.1.0  Production
    ...

It is important to convey to Oracle the results of this query when you report problems with the software.

## Database Administrator Security and Privileges

To perform the administrative tasks of an Oracle Database DBA, you need specific privileges within the database and possibly in the operating system of the server on which the database runs. Access to a database administrator's account should be tightly controlled.

This section contains the following topics:

- The Database Administrator's Operating System Account

- Database Administrator Usernames

### The Database Administrator's Operating System Account

To perform many of the administrative duties for a database, you must be able to execute operating system commands. Depending on the operating system on which Oracle Database is running, you might need an operating system account or ID to gain access to the operating system. If so, your operating system account might require operating system privileges or access rights that other database users do not require (for example, to perform Oracle Database software installation). Although you do not need the Oracle Database files to be stored in your account, you should have access to them.

See Also: Your operating system specific Oracle documentation. The method of creating the account of the database administrator is specific to the operating system.

### Database Administrator Usernames

Two user accounts are automatically created when Oracle Database is installed:

- `SYS` (default password: `CHANGE_ON_INSTALL`)

- `SYSTEM` (default password: `MANAGER`)

  Note: Both Oracle Universal Installer (OUI) and Database Configuration Assistant (DBCA) now prompt for `SYS` and `SYSTEM` passwords and do not accept the default passwords "change_on_install" or "manager", respectively. If you create the database manually, Oracle strongly recommends that you specify passwords for `SYS` and `SYSTEM` at database creation time, rather than using these default passwords. Please refer to "Protecting Your Database: Specifying Passwords for Users SYS and SYSTEM" for more information.

Create at least one additional administrative user and grant to that user an appropriate administrative role to use when performing daily administrative tasks. Do not use `SYS` and `SYSTEM` for these purposes.

Note Regarding Security Enhancements: In this release of Oracle Database and in subsequent releases, several enhancements are being made to ensure the security of default database user accounts. You can find a security checklist for this release in Oracle Database Security Guide. Oracle recommends that you read this checklist and configure your database accordingly.

#### SYS

When you create an Oracle Database, the user `SYS` is automatically created and granted the `DBA` role.

All of the base tables and views for the database data dictionary are stored in the schema `SYS`. These base tables and views are critical for the operation of Oracle Database. To maintain the integrity of the data dictionary, tables in the `SYS` schema are manipulated only by the database. They should never be modified by any user or database administrator, and no one should create any tables in the schema of user `SYS`. (However, you can change the storage parameters of the data dictionary settings if necessary.)

Ensure that most database users are never able to connect to Oracle Database using the `SYS` account.

#### SYSTEM

When you create an Oracle Database, the user `SYSTEM` is also automatically created and granted the `DBA` role.

The `SYSTEM` username is used to create additional tables and views that display administrative information, and internal tables and views used by various Oracle Database options and tools. Never use the `SYSTEM` schema to store tables of interest to non-administrative users.

#### The DBA Role

A predefined `DBA` role is automatically created with every Oracle Database installation. This role contains most database system privileges. Therefore, the DBA role should be granted only to actual database administrators.

Note: The DBA role does not include the `SYSDBA` or `SYSOPER` system privileges. These are special administrative privileges that allow an administrator to perform basic database administration tasks, such as creating the database and instance startup and shutdown. These system privileges are discussed in "Administrative Privileges".

## Database Administrator Authentication

As a DBA, you often perform special operations such as shutting down or starting up a database. Because only a DBA should perform these operations, the database administrator usernames require a secure authentication scheme.

This section contains the following topics:

- Administrative Privileges

- Selecting an Authentication Method

- Using Operating System Authentication

- Using Password File Authentication

### Administrative Privileges

Administrative privileges that are required for an administrator to perform basic database operations are granted through two special system privileges, `SYSDBA` and `SYSOPER`. You must have one of these privileges granted to you, depending upon the level of authorization you require.

Note: The `SYSDBA` and `SYSOPER` system privileges allow access to a database instance even when the database is not open. Control of these privileges is totally outside of the database itself. The `SYSDBA` and `SYSOPER` privileges can also be thought of as types of connections that enable you to perform certain database operations for which privileges cannot be granted in any other fashion. For example, you if you have the `SYSDBA` privilege, you can connect to the database by specifying `CONNECT AS SYSDBA`.

#### SYSDBA and SYSOPER

The following operations are authorized by the `SYSDBA` and `SYSOPER` system privileges:

System Privilege | Operations Authorized
--- | ---
`SYSDBA` | Perform `STARTUP` and `SHUTDOWN` operations `ALTER DATABASE`: open, mount, back up, or change character set `CREATE DATABASE` `DROP DATABASE` `CREATE SPFILE` `ALTER DATABASE ARCHIVELOG` `ALTER DATABASE RECOVER` Includes the `RESTRICTED SESSION` privilege Effectively, this system privilege allows a user to connect as user `SYS`.
`SYSOPER` | Perform `STARTUP` and `SHUTDOWN` operations `CREATE SPFILE` `ALTER DATABASE OPEN/MOUNT/BACKUP` `ALTER DATABASE ARCHIVELOG` `ALTER DATABASE RECOVER` (Complete recovery only. Any form of incomplete recovery, such as `UNTIL TIME|CHANGE|CANCEL|CONTROLFILE` requires connecting as `SYSDBA`.) Includes the `RESTRICTED SESSION` privilege This privilege allows a user to perform basic operational tasks, but without the ability to look at user data.

The manner in which you are authorized to use these privileges depends upon the method of authentication that you use.

When you connect with `SYSDBA` or `SYSOPER` privileges, you connect with a default schema, not with the schema that is generally associated with your username. For `SYSDBA` this schema is `SYS`; for `SYSOPER` the schema is `PUBLIC`.

#### Connecting with Administrative Privileges: Example

This example illustrates that a user is assigned another schema (`SYS`) when connecting with the `SYSDBA` system privilege. Assume that the sample user `oe` has been granted the SYSDBA system privilege and has issued the following statements:

    CONNECT oe/oe
    CREATE TABLE admin_test(name VARCHAR2(20));

Later, user `oe` issues these statements:

    CONNECT oe/oe AS SYSDBA
    SELECT * FROM admin_test;

User `oe` now receives the following error:

    ORA-00942: table or view does not exist

Having connected as `SYSDBA`, user `oe` now references the `SYS` schema, but the table was created in the `oe` schema.

See Also: "Using Operating System Authentication" "Using Password File Authentication"

### Selecting an Authentication Method

The following methods are available for authenticating database administrators:

- Operating system (OS) authentication

- A password file

  Notes: These methods replace the `CONNECT INTERNAL` syntax provided with earlier versions of Oracle Database. `CONNECT INTERNAL` is no longer supported. Operating system authentication takes precedence over password file authentication. If you meet the requirements for operating system authentication, then even if you use a password file, you will be authenticated by operating system authentication.

Your choice will be influenced by whether you intend to administer your database locally on the same machine where the database resides, or whether you intend to administer many different databases from a single remote client. Figure 1-2 illustrates the choices you have for database administrator authentication schemes.

Figure 1-2 Database Administrator Authentication Methods

Description of the illustration admin001.gif

If you are performing remote database administration, consult your Oracle Net documentation to determine whether you are using a secure connection. Most popular connection protocols, such as TCP/IP and DECnet, are not secure.

See Also: Oracle Database Net Services Administrator's Guide

#### Nonsecure Remote Connections

To connect to Oracle Database as a privileged user over a nonsecure connection, you must be authenticated by a password file. When using password file authentication, the database uses a password file to keep track of database usernames that have been granted the `SYSDBA` or `SYSOPER` system privilege. This form of authentication is discussed in "Using Password File Authentication".

#### Local Connections and Secure Remote Connections

You can connect to Oracle Database as a privileged user over a local connection or a secure remote connection in two ways:

- If the database has a password file and you have been granted the `SYSDBA` or `SYSOPER` system privilege, then you can connect and be authenticated by a password file.

- If the server is not using a password file, or if you have not been granted `SYSDBA` or `SYSOPER` privileges and are therefore not in the password file, you can use operating system authentication. On most operating systems, authentication for database administrators involves placing the operating system username of the database administrator in a special group, generically referred to as OSDBA. Users in that group are granted `SYSDBA` privileges. A similar group, OSOPER, is used to grant `SYSOPER` privileges to users.

### Using Operating System Authentication

This section describes how to authenticate an administrator using the operating system.

#### OSDBA and OSOPER

Two special operating system groups control database administrator connections when using operating system authentication. These groups are generically referred to as OSDBA and OSOPER. The groups are created and assigned specific names as part of the database installation process. The specific names vary depending upon your operating system and are listed in the following table:

Operating System Group | UNIX User Group | Windows User Group
--- | --- | ---
OSDBA | `dba` | `ORA_DBA`
OSOPER | `oper` | `ORA_OPER`

The default names assumed by the Oracle Universal Installer can be overridden. How you create the OSDBA and OSOPER groups is operating system specific.

Membership in the OSDBA or OSOPER group affects your connection to the database in the following ways:

- If you are a member of the OSDBA group and you specify `AS SYSDBA` when you connect to the database, then you connect to the database with the `SYSDBA` system privilege.

- If you are a member of the OSOPER group and you specify `AS SYSOPER` when you connect to the database, then you connect to the database with the `SYSOPER` system privilege.

- If you are not a member of either of these operating system groups and you attempt to connect as `SYSDBA` or `SYSOPER`, the `CONNECT` command fails.

  See Also: Your operating system specific Oracle documentation for information about creating the OSDBA and OSOPER groups

#### Preparing to Use Operating System Authentication

To enable operating system authentication of an administrative user:

1. Create an operating system account for the user.

2. Add the account to the `OSDBA` or `OSOPER` operating system defined groups.

#### Connecting Using Operating System Authentication

A user can be authenticated, enabled as an administrative user, and connected to a local database by typing one of the following SQL*Plus commands:

    CONNECT / AS SYSDBA
    CONNECT / AS SYSOPER

For a remote database connection over a secure connection, the user must also specify the net service name of the remote database:

    CONNECT /@net_service_name AS SYSDBA
    CONNECT /@net_service_name AS SYSOPER

See Also: SQL*Plus User's Guide and Reference for syntax of the `CONNECT` command

### Using Password File Authentication

This section describes how to authenticate an administrative user using password file authentication.

#### Preparing to Use Password File Authentication

To enable authentication of an administrative user using password file authentication you must do the following:

1. If not already created, create the password file using the `ORAPWD` utility:

       ORAPWD FILE=filename PASSWORD=password ENTRIES=max_users

2. Set the `REMOTE_LOGIN_PASSWORDFILE` initialization parameter to `EXCLUSIVE`. (This is the default).

   Note: `REMOTE_LOGIN_PASSWORDFILE` is a static initialization parameter and therefore cannot be changed without restarting the database.

3. Connect to the database as user `SYS` (or as another user with the administrative privileges).

4. If the user does not already exist in the database, create the user.

5. Grant the `SYSDBA` or `SYSOPER` system privilege to the user:

       GRANT SYSDBA to oe;

   This statement adds the user to the password file, thereby enabling connection `AS` `SYSDBA`.

   See Also: "Creating and Maintaining a Password File" for instructions for creating and maintaining a password file.

#### Connecting Using Password File Authentication

Administrative users can be connected and authenticated to a local or remote database by using the SQL*Plus `CONNECT` command. They must connect using their username and password and the `AS SYSDBA` or `AS SYSOPER` clause. For example, user `oe` has been granted the `SYSDBA` privilege, so `oe` can connect as follows:

    CONNECT oe/oe AS SYSDBA

However, user `oe` has not been granted the `SYSOPER` privilege, so the following command will fail:

    CONNECT oe/oe AS SYSOPER

Note: Operating system authentication takes precedence over password file authentication. Specifically, if you are a member of the OSDBA or OSOPER group for the operating system, and you connect as SYSDBA or SYSOPER, you will be connected with associated administrative privileges regardless of the username/password that you specify. If you are not in the OSDBA or OSOPER groups, and you are not in the password file, then attempting to connect as `SYSDBA` or as `SYSOPER` fails.

See Also: SQL*Plus User's Guide and Reference for syntax of the `CONNECT` command

## Creating and Maintaining a Password File

You can create a password file using the password file creation utility, `ORAPWD`. For some operating systems, you can create this file as part of your standard installation.

This section contains the following topics:

- Using ORAPWD

- Setting REMOTE_LOGIN_ PASSWORDFILE

- Adding Users to a Password File

- Maintaining a Password File

### Using ORAPWD

When you invoke this password file creation utility without supplying any parameters, you receive a message indicating the proper use of the command as shown in the following sample output:

    > orapwd
    Usage: orapwd file=<fname> password=<password> entries=<users> force=<y/n>

    where
      file - name of password file (mand),
      password - password for SYS (mand),
      entries - maximum number of distinct DBAs and OPERs (opt),
      force - whether to overwrite existing file (opt)
    There are no spaces around the equal-to (=) character.

The following command creates a password file named `acct.pwd` that allows up to 30 privileged users with different passwords. In this example, the file is initially created with the password `secret` for users connecting as `SYS`.

    orapwd FILE=acct.pwd PASSWORD=secret ENTRIES=30

The parameters in the `ORAPWD` utility are described in the sections that follow.

FILE

  This parameter sets the name of the password file being created. You must specify the full path name for the file. The contents of this file are encrypted, and the file cannot be read directly. This parameter is mandatory.

  The types of filenames allowed for the password file are operating system specific. Some operating systems require the password file to adhere to a specific format and be located in a specific directory. Other operating systems allow the use of environment variables to specify the name and location of the password file. For name and location information for the Unix and Linux operating systems, see Administrator's Reference for UNIX-Based Operating Systems. For Windows, see Platform Guide for Microsoft Windows. For other operating systems, see your operating system documentation.

  If you are running multiple instances of Oracle Database using Oracle Real Application Clusters, the environment variable for each instance should point to the same password file.

  Caution: It is critically important to the security of your system that you protect your password file and the environment variables that identify the location of the password file. Any user with access to these could potentially compromise the security of the connection.

PASSWORD

  This parameter sets the password for user `SYS`. If you issue the `ALTER USER` statement to change the password for `SYS` after connecting to the database, both the password stored in the data dictionary and the password stored in the password file are updated. This parameter is mandatory.

  Note: You cannot change the password for `SYS` if `REMOTE_LOGIN_PASSWORDFILE` is set to `SHARED`. An error message is issued if you attempt to do so.

ENTRIES

  This parameter specifies the number of entries that you require the password file to accept. This number corresponds to the number of distinct users allowed to connect to the database as `SYSDBA` or `SYSOPER`. The actual number of allowable entries can be higher than the number of users, because the `ORAPWD` utility continues to assign password entries until an operating system block is filled. For example, if your operating system block size is 512 bytes, it holds four password entries. The number of password entries allocated is always a multiple of four.

  Entries can be reused as users are added to and removed from the password file. If you intend to specify `REMOTE_LOGIN_PASSWORDFILE=EXCLUSIVE`, and to allow the granting of `SYSDBA` and `SYSOPER` privileges to users, this parameter is required.

  Caution: When you exceed the allocated number of password entries, you must create a new password file. To avoid this necessity, allocate a number of entries that is larger than you think you will ever need.

FORCE

  This parameter, if set to `Y`, enables you to overwrite an existing password file. An error is returned if a password file of the same name already exists and this parameter is omitted or set to `N`.

### Setting REMOTE_LOGIN_ PASSWORDFILE

In addition to creating the password file, you must also set the initialization parameter `REMOTE_LOGIN_PASSWORDFILE` to the appropriate value. The values recognized are:

- `NONE`: Setting this parameter to `NONE` causes Oracle Database to behave as if the password file does not exist. That is, no privileged connections are allowed over nonsecure connections.

- `EXCLUSIVE`: (The default) An `EXCLUSIVE` password file can be used with only one database. Only an `EXCLUSIVE` file can be modified. Using an `EXCLUSIVE` password file enables you to add, modify, and delete users. It also enables you to change the `SYS` password with the `ALTER USER` command.

- `SHARED`: A `SHARED` password file can be used by multiple databases running on the same server. However, the file cannot be modified. This means that you cannot add users to a `SHARED` password file. All users needing `SYSDBA` or `SYSOPER` system privileges must be added to the password file when `REMOTE_LOGIN_PASSWORDFILE` is set to `EXCLUSIVE`. After all users are added, you can change `REMOTE_LOGIN_PASSWORDFILE` to `SHARED`, and then share the file.

  This option is useful if you have one or more DBAs administering multiple databases.

If `REMOTE_LOGIN_PASSWORDFILE` is set to `EXCLUSIVE` or `SHARED` and the password file is missing, this is equivalent to setting `REMOTE_LOGIN_PASSWORDFILE` to `NONE`.

### Adding Users to a Password File

When you grant `SYSDBA` or `SYSOPER` privileges to a user, that user's name and privilege information are added to the password file. If the server does not have an `EXCLUSIVE` password file (that is, if the initialization parameter `REMOTE_LOGIN_PASSWORDFILE` is `NONE` or `SHARED`, or the password file is missing), Oracle Database issues an error if you attempt to grant these privileges.

A user's name remains in the password file only as long as that user has at least one of these two privileges. If you revoke both of these privileges, Oracle Database removes the user from the password file.

Creating a Password File and Adding New Users to It

Use the following procedure to create a password and add new users to it:

1. Follow the instructions for creating a password file as explained in "Using ORAPWD".

2. Set the `REMOTE_LOGIN_PASSWORDFILE` initialization parameter to `EXCLUSIVE`. (This is the default.)

   Note: `REMOTE_LOGIN_PASSWORDFILE` is a static initialization parameter and therefore cannot be changed without restarting the database.

3. Connect with `SYSDBA` privileges as shown in the following example:

       CONNECT SYS/password AS SYSDBA

4. Start up the instance and create the database if necessary, or mount and open an existing database.

5. Create users as necessary. Grant `SYSDBA` or `SYSOPER` privileges to yourself and other users as appropriate. See "Granting and Revoking SYSDBA and SYSOPER Privileges", later in this section.

#### Granting and Revoking SYSDBA and SYSOPER Privileges

If your server is using an `EXCLUSIVE` password file, use the `GRANT` statement to grant the `SYSDBA` or `SYSOPER` system privilege to a user, as shown in the following example:

    GRANT SYSDBA TO oe;

Use the `REVOKE` statement to revoke the `SYSDBA` or `SYSOPER` system privilege from a user, as shown in the following example:

    REVOKE SYSDBA FROM oe;

Because `SYSDBA` and `SYSOPER` are the most powerful database privileges, the `WITH ADMIN OPTION` is not used in the `GRANT` statement. That is, the grantee cannot in turn grant the `SYSDBA` or `SYSOPER` privilege to another user. Only a user currently connected as `SYSDBA` can grant or revoke another user's `SYSDBA` or `SYSOPER` system privileges. These privileges cannot be granted to roles, because roles are available only after database startup. Do not confuse the `SYSDBA` and `SYSOPER` database privileges with operating system roles.

See Also: Oracle Database Security Guide for more information on system privileges

#### Viewing Password File Members

Use the `V$PWFILE_USERS` view to see the users who have been granted `SYSDBA` or `SYSOPER` system privileges for a database. The columns displayed by this view are as follows:

Column | Description
--- | ---
`USERNAME` | This column contains the name of the user that is recognized by the password file.
`SYSDBA` | If the value of this column is `TRUE`, then the user can log on with `SYSDBA` system privileges.
`SYSOPER` | If the value of this column is `TRUE`, then the user can log on with `SYSOPER` system privileges.

### Maintaining a Password File

This section describes how to:

- Expand the number of password file users if the password file becomes full

- Remove the password file

#### Expanding the Number of Password File Users

If you receive the file full error (`ORA-1996`) when you try to grant `SYSDBA` or `SYSOPER` system privileges to a user, you must create a larger password file and regrant the privileges to the users.

Replacing a Password File

Use the following procedure to replace a password file:

1. Identify the users who have `SYSDBA` or `SYSOPER` privileges by querying the `V$PWFILE_USERS` view.

2. Delete the existing password file.

3. Follow the instructions for creating a new password file using the `ORAPWD` utility in "Using ORAPWD". Ensure that the `ENTRIES` parameter is set to a number larger than you think you will ever need.

4. Follow the instructions in "Adding Users to a Password File".

#### Removing a Password File

If you determine that you no longer require a password file to authenticate users, you can delete the password file and then optionally reset the `REMOTE_LOGIN_PASSWORDFILE` initialization parameter to `NONE`. After you remove this file, only those users who can be authenticated by the operating system can perform `SYSDBA` or `SYSOPER` database administration operations.

## Server Manageability

Oracle Database is a sophisticated self-managing database that automatically monitors, adapts, and repairs itself. It automates routine DBA tasks and reduces the complexity of space, memory, and resource administration. Several advisors are provided to help you analyze specific objects. The advisors report on a variety of aspects of the object and describe recommended actions. Oracle Database proactively sends alerts when a problem is anticipated or when any of the user-selected metrics.

In addition to its self-managing features, Oracle Database provides utilities to help you move data in and out of the database.

This section describes these server manageability topics:

- Automatic Manageability Features

- Data Utilities

### Automatic Manageability Features

Oracle Database has a self-management infrastructure that allows the database to learn about itself and use this information to adapt to workload variations and to automatically remedy any potential problem. This section discusses the automatic manageability features of Oracle Database.

#### Automatic Workload Repository

Automatic Workload Repository (AWR) is a built-in repository in every Oracle Database. At regular intervals, the database makes a snapshot of all its vital statistics and workload information and stores them in AWR. By default, the snapshots are made every 60 minutes, but you can change this frequency. The snapshots are stored in the AWR for a period of time (seven days by default) after which they are automatically purged.

See Also: Oracle Database Concepts and Oracle Database 2 Day DBA for overviews of the Automatic Workload Repository Oracle Database Performance Tuning Guide for details on using Automatic Workload Repository for statistics collection

#### Automatic Maintenance Tasks

Oracle Database uses the information stored in AWR to identify the need to perform routine maintenance tasks, such as optimizer statistics refresh and rebuilding indexes. Then the database uses the Scheduler to run such tasks in a predefined maintenance window.

See Also: Oracle Database Concepts for an overview of the maintenance window Chapter 23, "Managing Automatic System Tasks Using the Maintenance Window" for detailed information on using the predefined maintenance window

#### Server-Generated Alerts

Some problems cannot be resolved automatically and require the database administrator's attention. For these problems, such as space shortage, Oracle Database provides server-generated alerts to notify you when then problem arises. The alerts also provide recommendations on how to resolve the problem.

See Also: "Server-Generated Alerts" in this book for detailed information on using APIs to administer server-generated alerts

#### Advisors

Oracle Database provides advisors to help you optimize a number of subsystems in the database. An advisory framework ensures consistency in the way in which advisors are invoked and results are reported. The advisors are use primarily by the database to optimize its own performance. However, they can also be invoked by administrators to get more insight into the functioning of a particular subcomponent.

See Also: Oracle Database Concepts for an overview of the advisors Oracle Database 2 Day DBA for more detailed information on using the advisors

### Data Utilities

Several utilities are available to help you maintain the data in your Oracle Database. This section introduces two of these utilities:

- SQL*Loader

- Export and Import Utilities

  See Also: Oracle Database Utilities for detailed information about these utilities

#### SQL*Loader

SQL*Loader is used both by database administrators and by other users of Oracle Database. It loads data from standard operating system files (such as, files in text or C data format) into database tables.

#### Export and Import Utilities

Oracle export and import utilities enable you to move existing data in Oracle format between one Oracle Database and another. For example, export files can archive database data or move data among different databases that run on the same or different operating systems.