Question 1) Oracle Database 10g Administration

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Objective : Monitoring and Managing Storage
SubObjective : Tune Redo Writing and Archiving Operations

 

Single Answer Multiple Choice

 

You are maintaining your OLTP database in Oracle10g. While observing the performance of the database, you find that the log switch occurs more than once for every 20 minutes, affecting the database performance.

 

Which factor is responsible for frequent log switches?

 

A. the value of the UNDO_RETENTION initialization parameter
B. the value of the optimal redo log file size provided by the Redo Logfile Size Advisor
C. the online redo log files size
D. the number of redo log members in a group

 

Answer:
C. the online redo log files size

 

Tutorial:
The sizes of the online redo groups are responsible for frequent log switches. The LGWR process writes redo log entries from the redo log buffer to the online redo log files. There are two or more online redo log groups in the database. If a redo log file is full, the LGWR process starts writing redo log entries to the next available redo log file. This event is called log switch. If the size of the online redo log group is large, then the log switch event will occur less frequently. If the size of the online redo log group is small, then the log switch event will occur more frequently.

 

The option stating that the value of the UNDO_RETENTION initialization parameter is responsible for frequent log switches is incorrect. The UNDO_RETENTION parameter is used to specify the minimum amount of time for which the undo data will be retained in the undo segments.

 

The option stating that the value of the optimal redo log file size provided by the Redo Logfile Size Advisor is responsible for frequent log switches is incorrect. The optimal redo log file size is displayed by the value in the OPTIMAL_LOGFILE_SIZE column of the V$INSTANCE_RECOVERY view. It is recommended that you configure the size of redo log files to at least the value displayed in the OPTIMAL_LOGFILE_SIZE parameter.

 

The option stating that the number of the redo log members in a group is responsible for frequent log switches is incorrect. The log switch depends on the redo log file size and not on the number of members in a redo log group.

 

Reference:
Oracle Database 10g: Administration Workshop II
Chapter 13: Monitoring and Managing Storage

 

These questions are derived from the Self Test Software Practice Test for Oracle exam #IZ0-043: Oracle Database 10g: Administration II.

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