• About Me

    Maxwell Miranda
    Oracle DBA Consultant.
  • Category

  • Archives

  • My Blog Calendar

    February 2018
    M T W T F S S
    « Sep    
     1234
    567891011
    12131415161718
    19202122232425
    262728  
  • RSS Oracle Feeds

    • Can't access database after power outage
      I could access the database before the power outage. From what I've read, it is a problem with the environment variables, but they are correct. Not sure what else to add. C:\Documents and Settings\konoca>sqlplus / as sysdba SQL*Plus: Release 10.2.0.1.0 - Production on Wed Feb 21 09:17:08 2018 Copyright (c) 1982, 2005, Oracle. All rights reserved. ERR […]
    • Problems with RESET DATABASE
      Recently I wanted to do RESET DATABASE. Oracle documentation suggests the following commands connect target / startup force nomount reset database to incarnation 2 run { set until time "date time" restore controlfile from autobackup alter database mount restore database recover database } alter database open resetlogs In this view my db has given e […]
  • Advertisements

Control file – Contents

The control files of a database store the status of the physical structure of the database. The control file is absolutely crucial to database operation. It contains (but is not limited to) the following types of information:

* Database information (RESETLOGS SCN and their time stamp)
* Archive log history
* Tablespace and datafile records (filenames, datafile checkpoints, read/write status, offline or not)
* Redo threads (current online redo log)
* Database’s creation date
* database name
* current archive log mode
* Log records (sequence numbers, SCN range in each log)
* RMAN catalog
* Database block corruption information
* Database ID, which is unique to each DB
The location of the control files is specified through the control_files init param.

Backing up Controlfiles
When a controlfile (multiplexed or not) becomes unavailable (because for example of a media failure, the database cannot continue to operate.Because control files keep track of datafiles the control file should be backed up whenever a change is made to the database (alter database).
The command to back the control file up is: alter database backup controlfile to ‘filename’.

Size of control files
The size of the control files is governed by the following parameters:

* maxlogfiles
* maxlogmembers
* maxloghistory
* maxinstances
* control_file_record_keep_time

Sections
The controlfile contains the following sections:

* ARCHIVED LOG (reusable)
* BACKUP CORRUPTION (reusable)
* BACKUP DATAFILE (reusable)
* BACKUP PIECE (reusable)
* BACKUP REDOLOG (reusable)
* BACKUP SET (reusable)
* BACKUP SPFILE
* CKPT PROGRESS
* COPY CORRUPTION (reusable)
* DATABASE
* DATAFILE
* DATAFILE COPY (reusable)
* DATAFILE HISTORY
* DATABASE INCARNATION
* DELETED OBJECT (reusable)
* FILENAME
* FLASHBACK LOG
* INSTANCE SPACE RESERVATION
* LOG HISTORY (reusable)
* MTTR
* OFFLINE RANGE (reusable)
* RECOVERY DESTINATION
* REMOVABLE RECOVERY FILES
* RMAN STATUS
* RMAN CONFIGURATION
* REDO THREAD
* REDO LOG
* TABLESPACE
* TEMPORARY FILENAME
* THREAD INSTANCE NAME MAPPING
* PROXY COPY

The minimum number of days that a reusable record is kept in the controlfile is controlled by the control_file_record_keep_time parameter.These sections consist of records. The size, total number and number of used record are exposed through v$controlfile_record_section.

Advertisements