DBA Fundamentals

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.

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:

Connect to SQLPlus as the SYSTEM/MANAGER user.

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.

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.

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

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

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

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.

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

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

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.

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.

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?

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