Oracle Database – RMAN overview

Solution available for backup and recovery of Oracle Database
i) RMAN (Recovery Manager)
ii) User Managed backup (using o.s. commands like cp, copy..)

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RMAN (Recovery Manager) – is Oracle Database client that perform backup & restore task of oracle database.

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Components in RMAN

1. Target Database – is Oracle database which you want to backup or restore. You use RMAN client to connect to Target Database.

2. RMAN Client – is Oracle executable that interprets backup/restore related commands and direct server to execute those commands on Target Database.

3. RMAN Repository – RMAN maintains metadata about its operations, this RMAN metadata is called as RMAN repository and stored in control file of database.

4. Recovery Catalog (Optional Component) – Separate database schema to record RMAN activity against one or more TARGET database.

5. Media Manager (Optional Component) – Application for RMAN to interface with sequential media devices like tape library. Job of media manager is to load , label , unload ….media devices.

You can use RMAN with or Without Recovery Catalog and Media Manager

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Terminology in RMAN

a) Backup Set
– is one or more backup piece (physical files) written in format that only RMAN can access.

b) Image Copy – is bit-by-bit copy of database files created on Disk. This is equivalent to cp (on Linux) or copy (on windows).

* Backup Set is default method to backup, for image copy use BACKUP AS COPY while backup.

c) Hot backup – backup taken while Oracle Database is Up. (Database should be in “Archive Log” mode for hot backup)

d) Cold backup – backup taken while Oracle database is down or in mount state (NOT OPEN).

e) Full Backup – Backing up entire database is called as full backup

f) Incremental Backup – Backup of block level changes to database made after previous incremental/full backup.

g) “Level 0” Incremental backup – This backs up all blocks in database. This is equivalent to full backup.

h) “level 1” Incremental backup – This backs up database block changes after previous incremental backup.
If there is no level 0 incremental backup and you run level 1 incremental backup, RMAN will automatically make level 0 incremental backup.

i) Cumulative incremental backup – level 1 incremental backup which includes all blocks changed since most recent level 0 incremental backup.

j) Differential incremental backup – level 1 incremental backup which includes only block changed since most recent incremental backup.

By default, incremental backups are differential
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Basic Commands in RMAN
1. Start RMAN client
rman  (rman executable is in $ORACLE_HOME/bin)

2. Connect to target database (start RMAN client as shown above)
RMAN
> connect target sys@TNS_ALIAS_FOR_TARGET
like
RMAN> connect target sys@PROD

To connect to local database use operating system authentication
RMAN> connect target /

3. To exit from RMAN client
use EXIT like
RMAN> exit

4. To view current RMAN configuration

rman (To start RMAN Client)
RMAN> connect target / (to connect to target database)
RMAN> SHOW ALL

5. To backup database and archived redo while system is Up (Hot Backup)

Database should be in archive log mode

rman (To start RMAN Client)
RMAN> connect target / (to connect to target database)
RMAN> BACKUP DATABASE PLUS ARCHIVELOG;

6. To make consistent backup while database is not open (Database in No archive log mode)

rman (To start RMAN Client)
RMAN> connect target / (to connect to target database)
RMAN> SHUTDOWN IMMEDIATE (to shutdown database)
RMAN> STARTUP MOUNT;
RMAN> BACKUP DATABASE; (to backup database, no need to backup archived log as database is not open)
RMAN> ALTER DATABASE OPEN; (To Open Database )

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7. To make incremental backup

rman (To start RMAN Client)
RMAN> connect target / (to connect to target database)
RMAN> BACKUP INCREMENTAL LEVEL 0 DATABASE; (For incremental level 0 backup)
RMAN> BACKUP INCREMENTAL LEVEL 1 DATABASE; (For incremental level 1 backup)

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8. To List backup

rman (To start RMAN Client)
RMAN> connect target / (to connect to target database)
RMAN> LIST BACKUP ; (To list backup)
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9. To Delete Obsolete backup

rman (To start RMAN Client)
RMAN> connect target / (to connect to target database)
RMAN> DELETE OBSOLETE ; (To DELETE obsolete backup)
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Scripting of RMAN, Recovery?restore using RMAN and Advanced topics coming soon…

About the Author Atul Kumar

Oracle ACE, Author, Speaker and Founder of K21 Technologies & K21 Academy : Specialising in Design, Implement, and Trainings.

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Leave a Comment:

3 comments
Sridhar says December 14, 2009

Hi Atul,

Can you please post to steps to perform online backup on Oracle 9i RAC. With out RMAN.

Thanks in advance.

Regards,
Sridhar

Reply
kusal says September 28, 2010

HI ATUL,
ITS GUD TO UNDERSTAND AND STEPS ARE VERY CLEAR. CAN U PLEASE POST STEPS FOR RMAN ONLINE BACKUP OF ORACLE 10G.

HERE,
KUSAL

Reply
www.rmanbackup.com says September 29, 2010

Thank you so much for your precious information.

Reply
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