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Chapter 10 Restoring the Control File

Chapter 10 Restoring the Control File. Background. Decided to make the control file restore a chapter by itself since restoring the control file has many different options depending on how you are backing it up When you think of backups, think of recovery, especially applies to control files.

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Chapter 10 Restoring the Control File

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  1. Chapter 10Restoring the Control File

  2. Background • Decided to make the control file restore a chapter by itself since restoring the control file has many different options depending on how you are backing it up • When you think of backups, think of recovery, especially applies to control files

  3. Objectives • Restore control file from various types of backups • From autobackup • Using FRA • Using Recovery Catalog

  4. Restoring Control File Using Flash Recovery Area • Fairly straightforward if using FRA and autobackup feature: RMAN> connect target / RMAN> startup nomount; RMAN> restore controlfile from autobackup;

  5. Restoring Control File Using Flash Recovery Area • Not as straightforward if not using autobackup: RMAN> connect target / RMAN> startup nomount; RMAN> restore controlfile from 'C:\FRA\DB1\backupset\2006_09_23\01_mf_ncnnf_TAG20060923T02kc1vgsh.bck';

  6. Restoring Control File Using Recovery Catalog • When using the recovery catalog, very straightforward process: RMAN> connect target / RMAN> connect catalog rcat/rcat@recov RMAN> startup nomount; RMAN> restore controlfile;

  7. Determining the Database Identifier • Sometimes you need to know the DBID when restoring the control file • You can derive the DBID from an autobackup file • You can retrieve the DBID from RMAN output • You can write the DBID to the alert.log file • You can derive DBID from a file dump

  8. Writing the DBID to the Alert.log File • Be careful with this • Oracle Support may not like this • Writing messages to the alert.log file may result in Oracle Support’s refusal to use the alert.log file when diagnosing issues

  9. Restoring Control File with No Flash Recovery Area or Recovery Catalog • Many different scenarios • Using Autobackup, with RMAN Backup Piece in the Default Location • Using Autobackup, with RMAN Backup Piece in a Nondefault Location • Not Using Autobackup, with RMAN Backup Piece in the Default Location • Not Using Autobackup, with RMAN Backup Piece in Nondefault Location

  10. Restoring Control File to Nondefault Location • When using an autobackup: RMAN> connect target / RMAN> restore controlfile to 'C:\ctl.bk' from autobackup;

  11. Restoring Lost Copy of Multiplexed Control File • You can modify your initialization file so that it references only the good remaining control file(s) • You can copy a good control file to the location of the bad or missing control file • Note: It’s a best practice to multiplex your controlfiles

  12. Re-creating the Control File • You’ve experienced a failure and lost all of your control files, and you belatedly realize that you don’t have a good binary backup of the control file • You want to change a database setting that can be modified only by re-creating the control file • You are relocating a large number of datafiles, and you find it easier to re-create the control file with the new names and locations (instead of manually renaming the datafiles)

  13. Re-creating the Control File SQL> alter database backup controlfile to trace; SQL> show parameter user_dump_dest

  14. Naming a Trace File SQL> alter session set tracefile_identifier='MYTRACE'; <SID><Oracle process id><tracefile_identifier>.trc

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