This post explains the various scenarios for ORA-01157 and how to avoid them.
How to Recover from a Lost Datafile in Different Scenarios
In the event of a lost datafile or when the file cannot be accessed an ORA-01157 is reported followed by ORA-01110. Besides this, you may encounter error ORA-07360 : sfifi: stat error, unable to obtain information about file. A DBWR trace file is also generated in the background_dump_dest directory. If an attempt is made to shutdown the database normal or immediate will result in ORA-01116, ORA-01110 and possibly ORA-07368.
This post discusses various scenarios that may be causing this error and the solution/workaround for these. Throughout this post we refer to “backups” but if you have a valid physical standby database you may also use the standby database’s datafiles to recover the primary database.
Datafile not found by Oracle
– Unintentionally renamed or moved at the Operating System (OS) level. Simply restore the file to its original location and recover it
– Intentionally moved/renamed at OS level. You are re-organizing the datafile layout across various disks at the OS. After moving/renaming the file you will have to rename the file at the database level and recover it.
If the file is damaged/deleted and an attempt is made to start the database will result in ORA-01157, ORA-01110. Then depending upon the type of datafile lost different action needs to be taken. Check for a faulty hard disk. The file may have gone corrupt due to faulty disk. Replace the bad disk or create the file on a non-faulty disk.
Lost datafile could be in one of the following:
1. Temporary tablespace
If the datafile belongs to a temporary tablespace, you will have to simply offline drop the datafile and then drop the tablespace with including contents option. Thereafter, re-create the temporary tablespace.
2. Read Only Tablespace
In this case, you will have to restore the most recent backup of the read-only datafile. No media recovery is required as read-only tablespaces are not modified. Note however that media recovery will be required under the following conditions:
- The tablespace was in read-write mode when the last backup was taken and was made read-only afterward.
- The tablespace was in read-only mode when the last backup was taken and was made read-write in between and then again made read only
In either of the above cases, you will have to restore the file and do a media recovery using RECOVER DATAFILE statement. Apply all the necessary archived redo logs until you get the message “Media Recovery Complete”.
3. User Tablespace
Two options are available:
a. Recreate the user tablespace: If all the objects in the tablespace can be re-created (recent export is available; tables can be re-populated using scripts; SQL*Loader etc). Then, offline drop the datafile, drop the tablespace with including contents option. Thereafter, re-create the tablespace and re-create the objects in it.
b. Restore file from backup and do a media recovery: Database has to be in archivelog mode. If the database is in NOARCHIVELOG mode, you will only succeed in recovering the datafile if the redo to be applied to it is within the range of your online redo logs.
4. Index Tablespace
Two options are available:
a. Recreate the Index tablespace: If the index can be easily re-created using script or manual CREATE INDEX statement, then the best option is to offline drop the datafile, drop the index tablespace, and re-create it and recreate all indexes in it.
b. Restore file from backup and do a media recovery: If the index tablespace cannot be easily re-created, then restore the lost datafile from a valid backup and then do a media recovery on it.
5. System (and/or Sysaux) Tablespace
a. Restore from a valid backup and perform a media recovery on it.
b. Rebuild the database.
If neither backup of the datafile nor the full database backup is available, then rebuild database using full export, user level/table level export, scripts, SQL*Loader, standby, etc. to re-create and re-populate the database.
6. Undo Tablespace
While handling situation with lost datafile of an undo tablespace you need to be extra cautious so as not to lose active transactions in the undo segments. The preferred option, in this case, is to restore the datafile from backup and perform media recovery.
a. If the database was cleanly shutdown: Ensure that database was cleanly shutdown in NORMAL or IMMEDIATE mode. Update your init file with “undo_management=manual”. Restart the database. Drop and recreate the undo tablespace. Update your init file with “undo_management=auto”. Restart the database
b. If the database was NOT cleanly shutdown: If the database was shutdown aborted or crashed, you may not be able to drop the datafile as the undo segments may contain active transactions. You will need to restore the file from a backup and perform a media recovery.
7. Lost Controlfiles and Online Redo Logs
If the datafiles are in a consistent state, not needing media recovery, but you have lost all the controlfiles and online redologs, then while attempting to create controlfile using scripts will complain of missing redologs. In this case, use the RESETLOGS option of the create controlfile script and then open the database with RESETLOGS option.
8. Lost datafile and no backup
If there are no backups of the lost datafile then you can re-create the datafile with the same size as the original file and then apply all the archived redologs written since original datafile was created to the new version of the lost datafile.