Recovery of Read-Only Files with a Re-Created Control File

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Recovery of Read-Only Files with a Re-Created ControlFile

If a current or backup control file is unavailable for recovery,then you can execute a

CREATE

CONTROLFILE

statement as described in
"Create New Control File After Losing All Current and BackupControl Files". Read-only files should not be listed in the

CREATE

CONTROLFILE

statement so thatrecovery can skip these files. No recovery is required forread-only datafiles unless you restored backups of these files froma time when the datafiles were read/write.

After you create a new control file and attempt to mount andopen the database, the database performs a data dictionary checkagainst the files listed in the control file. For each file that isnot listed in the

CREATE

CONTROLFILE

statement but is present in the data dictionary, an entry iscreated for them in the control file. These files are named as

MISSING

nnnnn

,
where

nnnnn

isa five digit number starting with

0

.

After the database is open, rename the read-only files to theircorrect filenames by executing the

ALTER

DATABASE

RENAME

FILE

statement for all the files whose name is prefixed with

MISSING

.

To prepare for a scenario in which you might have to re-createthe control file, run the following statement when the database ismounted or open to obtain the

CREATE

CONTROLFILE

syntax:

ALTER DATABASE BACKUP CONTROLFILE TO TRACE;

This SQL statement produces a trace file that you can edit anduse as a script to re-create the control file. You can specifyeither the

RESETLOGS

or

NORESETLOGS

(default) keywords to generate

CREATE

CONTROLFILE

...

RESETLOGS

or

CREATE

CONTROLFILE

...

NORESETLOGS

versions of the script.

All the restrictions related to read-only files in

CREATE

CONTROLFILE

statements also applyto offline normal tablespaces, except that you need to bring thetablespace online after the database is open. You should leave outtempfiles
from the

CREATE

CONTROLFILE

statement and add them after database open.