RMAN RECOVERY SCENARIOS

 1) Complete Recovery  2) Loss of System datafile  3) Loss of Non-System datafile  4) Restoring a datafile if no backups  5) Restoring a tablespace  6) Loss of controlfiles  7) Loss of online redolog files Agenda

 Rman started from version 8  Rman backup is taken by oracle when dba submits it as a job  Rman backup does not backup by file(cb or hb or mirror image backups).Rman backup is content backup  Rman backups those used blocks(not by entire file)  Rman offers two types of backups 1)Regular backup(used blocks) 2)Incremental backup(changed blocks)  Rman takes less time and backup space  We need not depend on writing batch files like shell scripts in unix as Rman has its own scripting language which is platform independent INTRODUCTION TO RMAN

 Rman is capable of cleanup of obsolete archivelogs at the end of successful backup  From oracle 10g it started offering compressed backup(even less time/space)  Rman can perform backup of multiple destinations parallel  At the end of successful Rman backup we can ask Rman to check for the validity of the backup  Using Rman we can identify corrupted blocks and recover them  We need not depend on o/s schedulars like cron in unix as it has its own schedular

RESTORE AND RECOVERY CONCEPTS  We take the cold backup by shutting down the database followed by backup of C/R/D files at o/s level  If the database is in NALM(No archive log mode) and in case of database crash we can only go for simple restore(SR)  If the database is in ALM(Archive log mode) we have a choice of 1)Simple Restore(SR) 2)Restore+Recovery(R+R)  Recoveries are of two types 1)Complete Recovery(CR) 2)Incomplete Recovery(ICR)

 We use archive log files for recoveries  CR would be possible only if we have both *Current control file *Current online redolog file  If any of the above two files is missing then we endup performing ICR  ICR can be done in following ways *Until cancel *Until time *Until SCN

 At the end of ICR 1) we must open the database with resetlogs option 2)Immediately take one consistent cold backup  CR can be done in 2 ways *Online(If system dbf file is present) *Offline(If system dbf file is unavailable)  Whenever we perform ICR by opening the database with resetlogs option a new incarnation will be generated and all the backups taken with previous incarnations with orphand status will become invalid backups and they are not useful for restoring the database

Vva CONTROL FILE FIXED AREA ROTATION AREA Db name Contains names and locations of datafiles and redolofiles Timestamp of db creation Whether the db is in noarchive or archivelog mode Checkpoint info Log sequence number Last backup information Contains info of RMAN backups

COMPLETE RECOVERY

LOSS OF SYSTEM DATAFILE

LOSS OF NON SYSTEM DATAFILE

RESTORING A UNBACKED UP DATAFILE

RESTORING A TABLSEPACE

LOSS OF CONTROL FILES

LOSS OF ONLINE REDOLOG FILES

Thank you Pete N Ephanga Recovery Solution Engineer SunGard Availablity Services