RMAN RECOVERY SCENARIOS. 1) Complete Recovery 2) Loss of System datafile 3) Loss of Non-System datafile 4) Restoring a datafile if no backups.

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 nameContains names and locations of datafiles and redolofilesTimestamp of db creationWhether the db is in noarchive or archivelog modeCheckpoint infoLog sequence numberLast 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 EphangaRecovery Solution EngineerSunGard Availablity Services