Sunday, June 11, 2006

Control Files in Oracle 9i

MAXLOGFILES

MAXDATAFILES

MAXLOGMEMBERS

MAXINSTANCES

MAXLOGHISTORY


Control files contains the following :

  1. Database name & identifier

Name is taken either from init.ora DB_NAME parameter or name used in CREATE DATABASE command.

Identifier is recorded when the database is created.

  1. Time stamp of database creation

recorded at database creation.

  1. Tablespaces names

updated as tablespaces are added or dropped.

  1. Names & locations of datafiles & redo log files

updated as these are added, renamed or dropped from the database.

  1. Current redo log file sequence number

recorded during log switch

  1. Checkpoint information

recorded at checkpoints.

  1. Begin & end of undo segments


  1. Redo log archive information

location & status recorded when archiving occurs.

  1. Backup information

Location & status of backup recorded by Recovery Manager utility.

Sections of a Control file:

Reusable

Stores Recovery manager information such as backup datafile & back redolog file names. These are used in a circular manner & can only be reused by Recovery Man.

Not Reusable


A control file can be multiplexed upto 8 times.

Steps to multiplexing using SPFILE:

OMF managed control files:

Views for obtaining Control file information:

V$CONTROLFILE

(shows name & status)

SELECT * FROM V$CONTROLFILE;

V$PARAMETER

SELECT name, value FROM V$PARAMETER WHERE name='control_files';

v$CONTROLFILE_RECORD_SECTION

(shows information about the control file record sections)

SELECT type, record_size, records_total, records_used FROM v$CONTROLFILE_RECORD_SECTION WHERE TYPE='DATAFILE';

Note: records_total : shows the maximum no. of datafiles in this case.

PARAMETER control_files

(shows name,status & location)

SHOW PARAMETER control_files;

Information of several dynamic performance views are derived from control files such as:

v$TABLESPACE

V$LOG

v$ARCHIVE

V$BACKUP

V$DATAFILE

V$LOGFILE

V$ARCHIVED_LOG

V$DATABASE

V$TEMPFILE

V$LOGHIST



File information using Oracle Enterprise Manager Console :

Default username/Password

admin / admin

Navigate to :

Databases -> Storage


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