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Online Oracle Training for beginners and advanced - The most comprehensive Oracle tutorial

The authors do not guarantee or take any responsibility for the accuracy, or completeness of the information.

DBAs - Fundamentals II

 

Lesson 01 | Lesson 02 | Lesson 03 | Lesson 04 | Lesson 05 | Lesson 06 | Lesson 07 | Lesson 08 | Lesson 09 | Lesson 10 | Lesson 11 | Lesson 12 | Lesson 13 | Lesson 14 | Lesson 15 | Lesson 16 | Lesson 17 | Lesson 18 | Lesson 19 | Lesson 20 | Lesson 21 | Lesson 22 | Lesson 23 | Lesson 24 | Lesson 25 | Lesson 26 | Lesson 27 | Lesson 28 | Lesson 29 |

 

Lesson 01

“Human beings, by changing the inner attitudes of their minds, can change the outer aspects of their lives.” William James (1842 - 1910)

 

Read first then play the video:

   DBA-VIDEO -Oracle Background Processes

   

Oracle Fundamentals II Case Study

The Oracle Fundamentals II Case Study consists of the numbers of the most common DBA tasks to do its backup, recovery and network jobs. In your organization, you as a DBA, are expected to know at least how to:: allocate and re-size the memory space on the fly; understand the Oracle background processes; multiplex the Control Files; configure the Database Archive mode; Maintain Redo Log files; Duplex Archived Online Redo Log files; User-Managed COLD or OFFLINE Backups; User-Managed HOT or ONLINE backups; User-Managed Tablespaces and Datafiles backups; User-Managed Tablespace Restoration; Backup and Recovery using the EXPORT and IMPORT utilities; Create the RMAN repository; Use of the RMAN commands; Configure of the RMAN tool; Use the RMAN backup utility; Perform the recovery of a tablespace using the RMAN tool; Performing a Complete Backup using the RMAN tool; Performing incomplete database recoveries; Using the LIST and REPORT commands; Configuring a Listener using the “Net Manager” tool; and Configuring a Service Name using the “Net Manager” tool.

 

 

"First they ignore you, then they laugh at you, then they fight you, then you win." - Mahatma Gandhi (1869-1948)

 

Oracle Background Processes

 

Introduction

As a DBA, you are responsible to monitor and understand the functions of the Oracle background processes. Your job’s responsibilities dictate that you should at least be informed on the following basic fundamental subjects:

 

Oracle Background Processes

V$BGPROCESS

PMON

DBWn

ARC0

CKPT

SMON

RECO

Archive log configurations

ARCHIVE LOG LIST

DATABASE LOG MODE

The NOARCHIVELOG mode

The ARCHIVELOG mode

Commands:

ARCHIVE LOG LIST

 

Hands-on

Connect to a database

Connect to SQLPlus as the SYSTEM/MANAGER user.

SQL> CONNECT system/manager AS SYSDBA

 

View background processes

The Oracle Background Processes are programs or tasks that run on the Oracle background such as log writers, db writers, archives, checkpoint, etc.

Only view all the active Oracle background processes.

SQL> SELECT * FROM v$bgprocess

              WHERE PADDR <> '00'

/

This is the list of all the active background processes running in this database. Please note the following:

 

PMON - The Process Monitor (PMON) is responsible for performing recovery if a user process fails and rolls back the uncommitted transactions.

 

Database Writer

DBWn - The Database Writer (DBWn) is responsible for writing the changed blocks or dirty blocks in the database.

 

Archiver

ARC0 - The Archiver (ARC0) is responsible for writing the Online redo log files into the archive log destination.

 

Log writer

LGWR - The Log Writer (LGWR) is responsible for writing data from redo log buffers to the online redo log files.

 

Checkpoint process

CKPT - The checkpoint process (CKPT) is responsible for synchronizing the buffer cache with the data file. It updates all datafile headers and the control files.

 

System Monitor

SMON - The System Monitor process (SMON) is responsible for instance recovery.

 

Recoverer

RECO - The Re-coverer Process (RECO) is responsible for performing recovery of in-doubt transactions that often occur in distributed transactions.

 

Check a database is in a archivelog mode

As we mentioned, the Archiver (ARC0) is responsible for writing the Online Redo log files into the archive log destination. The database archives the Online Redo Log files so that DBAs can recover, to a point of failure, and to a point of time in case of a disaster and/or a media failure. In order to recover to the point of failure the database must be in the archivelog mode.

Check to see if the database is in the archivelog mode. The ARCHIVE LOG LIST command shows information about the database archive log mode status.

SQL> ARCHIVE LOG LIST

/

Notice that the DATABASE LOG MODE should be in archivelog mode. The automatic archival option must be enabled so that the Archive process will be able to archive the Online Redo log file into the Archive destination.

Make sure that you have enough disk space in the Archive destination. On the one of our Hands-On exercises, we well discuss how to change the database mode from the NOARCHIVELOG mode to the ARCHIVELOG mode.

 

“Education is the ability to listen to almost anything without losing your temper or your self confidence.” Robert Frost (1874 - 1963)

 

Questions:

Q: What are the Oracle Background Processes?

Q: Describe the V$BGPROCESS view.

Q: Describe the following background processes:

PMON

DBWn

ARC0

CKPT

LGWR

SMON

RECO

Q: Describe an archive log configuration.

Q: What does the ARCHIVE LOG LIST command?

Q: What are disadvantage and advantage of a database in the NOARCHIVELOG mode?

Q: What are disadvantage and advantage of a database in the ARCHIVELOG mode?

Q: What does the following SQL statememt?

SQL> SELECT * FROM v$bgprocess

              WHERE PADDR <> '00'

/

Q: How do you test that a database is in archivelog or not?