Starting Up and Shutting Down
This chapter describes the procedures for starting and stopping an Oracle7 database, and includes the following topics:
See Also: Trusted Oracle7 Server Administrator's Guide, for more information about starting up and shutting down Trusted Oracle7.
Oracle Server Manager User's Guide, for more information about performing specific tasks using Server Manager/GUI or Server Manager/LineMode.
This section includes the following topics:
To start up a database or instance, use either the Server Manager Startup Database dialog box or the STARTUP command (after you connect to Oracle7 with administrator privileges). You can start an instance and database in a variety of ways:
- start the instance without mounting a database
- start the instance and mount the database, but leave it closed
- start the instance, and mount and open the database in:
- unrestricted mode (accessible to all users)
Attention: You cannot start a database instance if you are connected to the database via a multi-threaded server process.
- RESTRICTED mode (accessible to DBAs only)
In addition, you can force the instance to start, or start the instance and have complete media recovery begin immediately. If your operating system supports the Oracle7 Parallel Server, you may start an instance and mount the database in either exclusive or shared mode.
See Also: Trusted Oracle7 Server Administrator's Guide, for more information about database startup and Trusted Oracle7.
Preparing to Start an Instance
There are several tasks you need to perform before you attempt to start an instance.
To Prepare to Start an Instance
1. Start Server Manager and connect with administrator privileges.
2. Specify a database name.
- specifying DB_NAME in the parameter file that starts the instance
3. Specify the parameter filename.
See Also: The specification of filenames is operating system-specific. See your operating system-specific Oracle documentation. If no filename is entered, Oracle7 uses the default filename.
Starting an Instance: Scenarios
The following scenarios describe the many ways in which you can start up an instance.
Note: You may encounter problems starting up an instance if control files, database files, or redo log files are not available. If one or more of the files specified by the CONTROL_FILES parameter do not exist or cannot be opened when you attempt to mount a database, Oracle7 returns a warning message and does not mount the database. If one or more of the datafiles or redo log files is not available or cannot be opened when attempting to open a database, Oracle7 returns a warning message and does not open the database.
Starting an Instance Without Mounting a Database
You might want to start an instance without mounting a database; this is usually the case only during database creation. To do this, use one of the following options of Server Manager:
Starting an Instance and Mounting a Database
You might want to start an instance and mount a database, but not open the database because you want to perform specific maintenance operations. For example, the database must be mounted but not open during the following tasks:
- adding, dropping, or renaming redo log files
- enabling and disabling redo log archiving options
Start an instance and mount the database, but leave it closed using one of the following options of Server Manager:
- performing full database recovery
Starting an Instance, and Mounting and Opening a Database
Normal database operation means that an instance is started and the database is mounted and open; this allows any valid user to connect to the database and perform typical data access operations.
Start an instance, and mount and open the database, using one of the following options of Server Manager:
Restricting Access to a Database at Startup
You might want to start an instance, and mount and open a database in restricted mode so that the database is available only to administrative personnel (not general database users). Use this mode of database startup when you need to accomplish one of the following tasks:
- perform structure maintenance, such as rebuilding indexes
- perform an export or import of database data
- perform a data load (with SQL*Loader)
Typically, all users with the CREATE SESSION system privilege can connect to an open database. Opening a database in restricted mode allows database access only to users with both the CREATE SESSION and RESTRICTED SESSION system privilege; only database administrators should have the RESTRICTED SESSION system privilege.
- temporarily prevent typical users from using data
Start an instance (and, optionally, mount and open the database) in restricted mode using one of the following options of Server Manager:
Later, you can make the database accessible to users who do not have the RESTRICTED SESSION system privilege.
Forcing an Instance to Start
In unusual circumstances, you might experience problems when attempting to start a database instance. A database instance should not be forced to start unless you are faced with the following:
- The current instance cannot be successfully shut down using either the Normal or Immediate radio buttons of the Shutdown Database dialog box (or an equivalent SHUTDOWN statement).
If one of these situations arises, you can usually solve the problem by starting a new instance (and optionally mounting and opening the database) using either of the following options of Server Manager:
- You experience problems when starting an instance.
Starting an Instance, Mounting a Database, and Starting Complete Media Recovery
If you know that media recovery is required, you can start an instance, mount a database to the instance, and have the recovery process automatically start by using the STARTUP command with the RECOVER option.
Starting in Exclusive or Parallel Mode
If your Oracle7 Server allows multiple instances to access a single database concurrently, you must choose whether to mount the database exclusively or in parallel.
Starting Up an Instance and Database: Example
The following statement starts an instance using the parameter file INITSALE.ORA, mounts and opens the database named SALES in exclusive mode, and restricts access to administrative personnel. The DBA is already connected with administrator privileges.
STARTUP OPEN sales PFILE=INITSALE.ORA EXCLUSIVE RESTRICT;
Automatic Database Startup at Operating System Start
Many sites use procedures to enable automatic startup of one or more Oracle7 instances and databases immediately following a system start. The procedures for doing this are specific to each operating system.
Starting Remote Instances
If your local Oracle7 Server is part of a distributed database, you might need to start a remote instance and database. Procedures for starting and stopping remote instances vary widely depending on communication protocol and operating system.
See Also: For more information about making a database available to non-privileged users, see "Restricting Access to an Open Database" .
For more information about recovering control files, database files and redo logs, see Chapter 24.
For more information about the side effects of aborting the current instance, see "Aborting an Instance" .
For more information about starting up in exclusive or parallel mode, see the Oracle7 Parallel Server Concepts & Administration manual.
For more information about the restrictions that apply when combining options of the STARTUP command, see the Oracle7 Server SQL Reference.
For more information about automatic startup procedure topics, see your operating system-specific Oracle documentation.
Altering Database Availability
You can make a database partially available by opening a previously mounted but closed database so that users can connect to and use the database.
The following sections explain how to alter a database's availability:
Mounting a Database to an Instance
When you need to perform specific administrative operations, the database must be started and mounted to an instance, but closed. This can be accomplished by starting the instance and mounting the database.
When mounting the database, you can indicate whether to mount the database exclusively to this instance or concurrently to other instances.
To mount a database to a previously started instance, use either of the following options:
- the Mount menu item of Server Manager
Use the following statement when you want to mount a database in exclusive mode:
- the SQL command ALTER DATABASE with the MOUNT option
ALTER DATABASE MOUNT;
See Also: For a list of operations that require the database to be mounted and closed, (and procedures to start an instance and mount a database in one step) see "Starting an Instance and Mounting a Database" .
Opening a Closed Database
You can make a mounted but closed database available for general use by opening the database. To open a mounted database, use either of the following options:
Use the following statement to open a mounted database:
ALTER DATABASE OPEN;
After executing this statement, any valid Oracle7 user with the CREATE SESSION system privilege can connect to the database.
Restricting Access to an Open Database
Under normal conditions, all users with the CREATE SESSION system privilege can connect to an instance. However, you can take an instance in and out of restricted mode. When an instance is in restricted mode, only users who have both the CREATE SESSION and RESTRICTED SESSION system privileges can connect to it. Typically, only administrators have the RESTRICTED SESSION system privilege.
Restricted mode is useful when you need to perform the following tasks:
- perform structure maintenance, such as rebuilding indexes
- perform an export or import of database data
- perform a data load (with SQL*Loader)
To place an instance in restricted mode, use the Restrict menu item of Server Manager or the SQL command ALTER SYSTEM with the ENABLE RESTRICTED SESSION option. After placing an instance in restricted mode, you might want to kill all current user sessions before performing any administrative tasks.
- temporarily prevent non-administrator users from using data
To lift an instance from restricted mode, use the Allow All menu item of Server Manager or the SQL command ALTER SYSTEM with the DISABLE RESTRICTED SESSION option.
See Also: For more information about killing sessions, see "Terminating Sessions" .
For more information about starting a database instance, and mounting and opening the database in restricted mode, see "Restricting Access to a Database at Startup" .
The following sections describe various shutdown procedures:
To initiate database shutdown, use either the Shutdown Database dialog box of Server Manager or the SQL command SHUTDOWN. Control is not returned to the session that initiates a database shutdown until shutdown is complete. Users who attempt connections while a shutdown is in progress receive a message like the following:
ORA-01090: shutdown in progress - connection is not permitted
Attention: You cannot shut down a database if you are connected to the database via a multi-threaded server process.
To shut down a database and instance, you must first be connected with administrator privileges. This condition applies whether you are using Server Manager/GUI or SQL commands.
See Also: Several special options and conditions of database shutdown that apply when using Trusted Oracle7 in OS MAC mode are not discussed in this section. For more information about database shutdown and Trusted Oracle7, see the Trusted Oracle7 Server Administrator's Guide.
Shutting Down a Database Under Normal Conditions
Normal database shutdown proceeds with the following conditions:
- No new connections are allowed after the statement is issued.
- Before the database is shut down, Oracle7 waits for all currently connected users to disconnect from the database.
To shut down a database in normal situations, use either of the following options of Server Manager:
- The next startup of the database will not require any instance recovery procedures.
Shutting Down a Database Immediately
Use immediate database shutdown only in the following situations:
- A power shutdown is going to occur soon.
Immediate database shutdown proceeds with the following conditions:
- The database or one of its applications is functioning irregularly.
- Current client SQL statements being processed by Oracle7 are terminated immediately.
- Any uncommitted transactions are rolled back. (If long uncommitted transactions exist, this method of shutdown might not complete quickly, despite its name.)
To shut down a database immediately, use either of the following options of Server Manager:
- Oracle7 does not wait for users currently connected to the database to disconnect; Oracle7 implicitly rolls back active transactions and disconnects all connected users.
- the Immediate radio button of the Shutdown database dialog box
- the SHUTDOWN command with the IMMEDIATE option
Aborting an Instance
You can shutdown a database instantaneously by aborting the database's instance. If possible, perform this type of shutdown only when in the following situations:
- The database or one of its applications is functioning irregularly and neither of the other types of shutdown work.
- You need to shut down the database instantaneously (for example, if you know a power shutdown is going to occur in one minute).
Aborting an instance shuts down a database and yields the following results:
- You experience problems when starting a database instance.
- Current client SQL statements being processed by Oracle7 are immediately terminated.
- Uncommitted transactions are not rolled back.
If both the normal and immediate shutdown options do not work, abort the current database instance immediately by using either of the following options of Server Manager:
- Oracle7 does not wait for users currently connected to the database to disconnect; Oracle7 implicitly disconnects all connected users.
- the Abort radio button of the Shutdown Database dialog box
- the SHUTDOWN command with the ABORT option
Using Parameter Files
The following sections include information about how to use parameter files:
To start an instance, Oracle7 must read a parameter file, which is a text file containing a list of instance configuration parameters. Often, although not always, this file is named INIT.ORA or INITsid.ORA, where sid is operating system-specific.
You can edit parameter values in a parameter file with a basic text editor; however, editing methods are operating system-specific.
Oracle7 treats string literals defined for National Language Support (NLS) parameters in the file as if they are in the database character set.
See Also: For more information about INITsid.ORA, see your operating system-specific Oracle documentation.
The Sample Parameter File
A sample parameter file (INIT.ORA or INITsid.ORA) is included in the Oracle7 distribution set. This sample file's parameters are adequate for initial installations of an Oracle7 database. After your system is operating and you have some experience with Oracle7, you will probably want to change some parameter values.
See Also: For more information about optimizing a database's performance using the parameter file, see the Oracle7 Server Tuning manual.
The Number of Parameter Files
Each Oracle7 database has at least one parameter file that corresponds only to that database. This way, database-specific parameters (such as DB_NAME and CONTROL_FILES) in a given file always pertain to a particular database. It is also possible to have several different parameter files for a single database. For example, you can have several different parameter files for a single database so you can optimize the database's performance in different situations.
The Location of the Parameter File in Distributed Environments
Server Manager must be able to read a database's parameter file to start a database's instance. Therefore, always store a database's parameter file on the computer executing Server Manager.
For example, in non-distributed processing installations, the same computer executes Oracle7 and Server Manager; therefore, this computer has the parameter file stored on one of its disk drives.
However, in distributed processing installations, local client workstations can execute Server Manager to administer a database stored on a remote machine. In this type of configuration, the local client machines must each store a copy of the parameter file for the corresponding databases.
See Also: For more information about using administering Oracle7 in a distributed environment, see Oracle7 Server Distributed Systems, Volume I.
For information concerning the setup and implementation of Server Manager, see your operating system-specific Oracle documentation.