1. Is 221: Database Administration
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Lecture 3: Oracle Database Instance Management
Starting Up and Shutting Down

2. Oracle Database Instance Management
A parameter file: is a file that contains a list of initialization parameters and a value for each parameter.
The properties of an Oracle instance are specified using instance initialization parameters. When the instance is started, an initialization parameter file is read, and the instance is configured accordingly.
Managing an Oracle instance includes configuring parameters that affect the basic operation of the Oracle instance. These parameters are called initialization parameters.
The Oracle instance reads initialization parameters from a file at startup.
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3. Oracle Database Instance Management
After being read from a file, initialization parameters are retained in memory, where the values for many of them can be changed dynamically.
There are two types of parameter files.
Parameter Files
1- Server Parameter File (SPFILE)
2- Text Initialization Parameter File (PFILE)
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4. :Parameter Files 1- Server Parameter File (SPFILE):
It is a binary file that can be written to and read by the database.
Location: It is stored on the host computer on which Oracle Database is running.
It must not be edited manually.
Changes are made when you use Database Control to modify one or more initialization parameters, or when Oracle Database itself makes changes for self-tuning purposes.
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5. Parameter Files: 2- Text Initialization Parameter File (PFILE):
It is a text file that can be read by the Oracle instance.
You can change a text initialization parameter file with a text editor, but changes do not take effect until you restart the Oracle instance.
When you start the instance with this type of file, you can still change many initialization parameters dynamically with Database Control.
The change is lost when you restart the database instance without saving your changes.
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6. Oracle Database Instance Startup
Stages for Starting Up a Database:
NOMOUNT
MOUNT
OPEN
When you start up a database, you create an instance of that database and you determine the state of the database.
To start an instance, the database must read instance configuration parameters (the initialization parameters) from either a server parameter file (SPFILE) or a text initialization parameter file(PFILE).
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7. Oracle Database Instance Startup
You start up the instance using one of the following methods:
1- Oracle Enterprise Manager.
2- SQL Plus STARTUP command.
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8. Starting Up an Oracle Database Instance: NOMOUNT
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9. Starting Up an Oracle Database Instance: NOMOUNT
In the platform-specific default location, Oracle Database locates your initialization parameter file by examining file names in the following order:
1. spfileORACLE_SID.ora
2. spfile.ora
3. initORACLE_SID.ora
( Allocating the SGA, Starting the background processes, Opening the alert<SID>.log file and the trace files. )
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10. Starting Up an Oracle Database Instance: MOUNT
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11. Starting Up an Oracle Database Instance: MOUNT
Mounting a database includes the following tasks:
Associating a database with a previously started instance.
Locating and opening the control files specified in the parameter file.
Reading the control files to obtain the names and statuses of the data files and online redo log files.
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12. Starting Up an Oracle Database Instance: OPEN
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13. Starting Up an Oracle Database Instance: OPEN
A normal database operation: means that an instance is started and the database is mounted and opened.
With a normal database operation, any valid user can connect to the database and perform typical data access operations.
Opening the database includes the following tasks:
Opening the online data files.
Opening the online redo log files.
If any of the data files or online redo log files are not present when you attempt to open the database, then the Oracle server returns an error.
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14. Oracle Database Instance Startup
SQL Commands:
STARTUP; = STARTUP OPEN;
starts an instance, reads the initialization parameters from the default location, and then mounts and opens the database.
STARTUP PFILE = $Oracle_Home/dbs/initdb01.ora
Start up the instance pointing to this initialization parameter file.
STARTUP NOMOUNT;
STARTUP MOUNT;
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15. Additional Instance Startup Options
Two additional options for Starting up an Instance:
Restrict access to the database.
Force the instance to start.
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16. Restricted Access to the Database
Instance can be started in Restricted Mode so that the instance is available only to administrative personnel (not general database users).
Only database administrators should have the RESTRICTED SESSION system privilege.
HOW to access? when the instance is in restricted mode, a database administrator cannot access the instance remotely through an Oracle Net listener, but can only access the instance locally from the machine that the instance is running on.
SQL Commands:
ALTER SYSTEM ENABLE RESTRICTED SESSION;
STARTUP RESTRICT;
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17. Forcing an Instance to Startup
In unusual circumstances, you might experience problems when attempting to start a database instance.
Because a previous instance might not have been shutdown cleanly. For example, one of the instance's processes might not have terminated properly.
In such situations, the database can return an error during normal instance startup.
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18. Forcing an Instance to Startup
Instance can be forced to start up using the Force option and that will terminate all remnant Oracle processes of the previous instance before starting the new instance.
SQL Commands:
STARTUP FORCE;
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19. Oracle Database Instance Shutdown
Modes for Shutting down a Database:
ABORT
IMMEDIATE
TRANSACTIONAL
NORMAL
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20. Oracle Database Instance Shutdown
If the instance is already started it can be Shutdown.
Shutdown modes are progressively more accommodating of current activity in this order:
ABORT: This is typically used: when no other form of shutdown works (NORMAL and IMMEDIATE), when there are problems when starting the instance, or when you need to shut down immediately because of an impending situation.
IMMEDIATE: Uncommitted transactions are rolled back.
TRANSACTIONAL: Allows transactions to finish.
NORMAL: Waits for sessions to disconnect.
If you consider the amount of time that it takes to perform the shutdown, you find that ABORT is the fastest and NORMAL is the slowest.
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21. Shutdown Modes Consistent database (clean database) On the way down:
Uncommitted changes rolled back, for IMMEDIATE.
Database buffer cache written to data files.
Resources released.
During
NORMAL or
TRANSACTIONAL
IMMEDIATE
On the way up:
No instance recovery.
Consistent database
(clean database)
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22. Inconsistent database
Shutdown Modes
During
ABORT or
Instance failure
STARTUP FORCE
On the way down:
Uncommitted changes not rolled back.
Modified buffers not written to data files.
On the way up:
Online redo log files used to reapply changes.
Undo segments used to roll back uncommitted changes.
Resources released.
Inconsistent database
(dirty database)
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23. Managing Oracle instance through the Enterprise Manager
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24. Startup step#1
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25. Startup step#2 Information Systems Department
Starting the Oracle Database Instance
If the database is currently not started when you go to the Enterprise Manager Database Control page, Click Startup to start the instance.
Then the Startup/Shutdown: Specify Host and Target Database Credentials page is displayed.
Enter the host credentials and database credentials. Select Save as Preferred Credentials. Click OK.
Then the Startup/Shutdown: Confirmation page is displayed.
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26. Startup step#3 Information Systems Department
Starting the Oracle Database Instance (continued)
Optionally, click the Advanced Options button, to choose the startup mode.
To start an instance in restricted mode, select “ restrict access to database” option on the advanced startup options page.
To force an instance to start up, select “ force the instance to start” option on the advanced startup options page.
Click Yes to start the instance and open the database.
Then the Startup/Shutdown: Activity page is displayed.
After the instance is started and the database is open, the Login page is displayed.
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27. Startup step#4
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28. Startup step#5
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29. Startup step#6
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30. Shutdown step#1
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31. Shutdown step#2
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32. Shutdown step#3 Information Systems Department
Starting the Oracle Database Instance (continued)
Enter the username and password to log in to Enterprise Manager Database Control. Click Login.
Then the Database home page is displayed.
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33. Shutdown step#4 Information Systems Department
Shutting the Oracle Database Instance (continued)
Optionally, click the Advanced Options button, to select the mode of the shutdown: Normal, Transactional, Immediate, or Abort.
Click Yes to perform the shutdown operation.
The Startup/Shutdown: Activity Information page appears. Click Refresh.
Then the Database home page is displayed.
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34. Shutdown step#5 Information Systems Department
Shutting the Oracle Database Instance (continued)
After the instance is shutdown and the Database home page is displayed, you can restart your instance.
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