Database recovery considerations

In every database system, system or hardware failures can occur. If a failure occurs and affects the database, the database must be recovered. Before you begin your database recovery, read the following information carefully.

Recovery media

On SQL Server databases, to perform a database recovery from tape, you need a tape drive and the most recent successful backup tapes. More than one tape may be required if the most recent tape is corrupt or the most recent backup contains a corrupt datafile.

Only disk backups are supported for Oracle for Windows databases. (If required, site-specific third-party add-on backup tools can be used to extend these disk backups to tape and/or enterprise mechanisms already in use at the site.) To perform a database recovery from disk, you need access to the area on the disk that holds the database backups.

Type of database recovery

The two general types of recoveries are D-to-D-to-T recovery and disk recovery. Only disk recovery is supported for Oracle for Windows. The following error messages indicate the type of recovery you must perform.

Error message	Procedure
ORA-01113: file n needs media recovery ORA-01110: data file n: 'file_name'
ORA-00204 "error in reading controlfile 'name' block num, # blocks num" ORA-01113 "file name needs recovery" ORA-01178 "file name created before last CREATE CONTROLFILE, cannot recreate." ORA-01116 "error in opening database file n"	Media recovery methods explains which recovery method to use
ORA=00257: archiver is stuck. CONNECT INTERNAL only, until freed.	or Recovering when the disk is full from transaction logs
ORA-00255: error archiving log name of thread num, sequence # num	Clearing corrupt redo log files