1. Oracle’s Backup and Recovery Tool
Introduction to RMAN
Oracle’s Backup and Recovery Tool
Recovery MANager

2. Introduction to RMAN Oracle’s Backup and Recovery Tool
Recovery MANager
Presented by Paul Hebert/ITEC

3. What RMAN does
RMAN creates backups and restores Oracle database files to tape or disk
Datafiles
Controlfiles
Parameter files
Archive logs
RMAN will perform consistent and inconsistent database backups
Consistent backups must be performed with the target database shut down
Inconsistent (hot) backups require the target database is in archivelog mode
Inconsistent backups require logical recovery using archivelogs
RMAN manages information about generated backup media files
Backup information is stored in control files
Backup information optionally stored in an RMAN repository catalog
RMAN can perform point-in-time restoration

4. Other RMAN capabilities
RMAN uses disk or tape channels to read and write to disk or tape media
RMAN tape devices rely on 3rd party Media Manager software
RMAN permits restartable backups if you have a specific time window within which backups are permitted
RMAN can create image copies usable by user-scripted restore procedures
Exact copies of target database files
RMAN can create backup sets instead of traditional image copies
RMAN has a command-line interface (rman) and is also integrated with Grid Control

5. Backup Sets Backup Sets
Backup Sets are logical groupings of backed-up database files
Backup sets have a unique ID and may have a ‘TAG’ for RMAN identification
Backup sets consist of one or more individual files called backup pieces.
Backup piece files contain the data blocks from a backup
Backup Sets
RMAN recovery using Backup Sets
The recovery process identifies the target SCN or date to which to recover
Needed blocks are retrieved from the appropriate backup set pieces
Data files are reconstructed from the needed blocks
Backup set media options
Backup sets can be written to disk or tape
Backup sets can be compressed by omitting unchanged blocks
Tape backup sets can be encrypted (via Oracle Secure Backup)
Tape backups must use backup sets

6. RMAN Backups

7. RMAN Channels Channels
A stream of data to a device using one server session
Server session performs the backup, restore and recovery
Channels can be configured with device-specific settings
Channels are automatically allocated, or manually allocated
Channels
RUN {
ALLOCATE CHANNEL c1 DEVICE TYPE sbt;
BACKUP DATABASE PLUS ARCHIVELOG; }
BACKUP DATAFILE 3;
RESTORE TABLESPACE users;

8. RMAN Media Managers RMAN> CONFIGURE DEVICE TYPE sbt PARALLELISM 1;
RMAN> CONFIGURE DEFAULT DEVICE TYPE TO sbt;
RMAN> CONFIGURE CHANNEL DEVICE TYPE sbt PARMS 'ENV=(NSR_SERVER=bksvr1)';
RMAN> BACKUP DATABASE;
Two types of device type – disk and sbt
RMAN has an open API for communicating with Tape and other media manager software
RMAN sends labeled streams of bytes to the media manager during backup
The labeled streams are returned by the media manager during RMAN restore operations
Media Manager vendors have specific installation instructions that vary by vendor
Refer to vendors for detailed installation and use instructions

9. RMAN backup output media
Backup Set
RMAN-proprietary storage of backed-up data blocks
Consist of a Backup Set identifier plus associated backup set files or pieces
Can only be restored using RMAN
Image Copy
Equivalent to file copies of original database files
RMAN considers user-managed backups as Image Copies
Contain ALL data blocks – no compression

10. RMAN Tags Backup sets or image copies can be labeled with a text TAG
RMAN commands can select backup sets or copies using the TAG
TAGs are visible in RMAN list or report output
BACKUP AS COPY DATABASE TAG=full_cold_copy;
BACKUP AS COPY COPY OF DATABASE FROM TAG=full_cold_copy TAG=new_full_cold_copy;

11. Full backup is equivalent to incremental level 0
RMAN backup types
Full backup
Backup of all specified database file blocks
Independent of when database files were last backed up
Not used in incremental backup strategies
Incremental backup
Backup of blocks changed since last incremental backup
SCN used to identify changed blocks
Level 0 incremental backup
Level 1 incremental backup
Full backup is equivalent to incremental level 0

12. Incremental Backup Types
Level 0 incremental backups
Backup of all blocks in specified database files
Independent of when files were last backed up
Base for subsequent Level 1 backups

13. Incremental Backup Types
Level 1 incremental backups
Differential backup
Contain all blocks changed after the most recent incremental backup at level 1 or 0
Differential backups remain smaller and quicker to perform
Differential backups are slower to restore requiring changes in multiple earlier incremental backups
Cumulative backup
Contain all blocks changed after the most recent incremental backup at level 0
Cumulative backups become much larger over time
Cumulative backups are quicker to restore

14. Other RMAN capabilities
RMAN can report, validate, remove or protect backup files
RMAN performance controls
RMAN can throttle disk I/O rate during backup and restore
RMAN can limit the number and size of backup set files
RMAN can use a Block Change Tracking file to identify changed blocks
Bitmap file created automatically by Level 0 backup if configured
RMAN can now avoid rescanning database files for changed blocks
(blocks with newer SCN than in previous backup sets)
Loss of change tracking file is harmless – recreated by next Level 0
Change Tracking file can introduce database overhead
you need to evaluate if it is worth the extra performance hit
RMAN and missing Level 0 backups
RMAN will create a missing Level 0 backup automatically when asked to perform a Level 1 backup

15. Other RMAN capabilities
RMAN actions can be scripted and scheduled using cron or dbms_job
RMAN can backup and restore your Flash Recovery Area
RMAN can clone (duplicate) databases using the AUXILIARY connection
RMAN can use and manage ASM files
RMAN can switch an instance to use a copy of a database or datafiles

16. What doesn’t RMAN do?
RMAN does not automatically enforce your retention policies
RMAN does not automatically delete expired backup files
RMAN does not automatically detect missing backup files
RMAN does not backup any other types of files
Oracle code tree
Other operating system files
Alert logs and traces
Oracle Wallet files
RMAN is not upward or downward version compatible
You must backup 10g databases with 10g RMAN!
You can only backup 9i databases with 9i RMAN!
10g and 9i can’t share a repository!

17. Cumulative Incremental Backup Strategy
Increasing backup set size and backup duration
Faster recovery
Level 0 Cumulative Incremental (Full) - Day 1
Level 1 Cumulative Incremental - Day 2
Level 1 Cumulative Incremental - Day 3
Restorable to Day 1
All blocks backed up
Restorable to Day 2 using Level 0 Day 1 and Level 1 Day 2
Contains only blocks changed since Level 0 on Day 1
Restorable to Day 3 using Level 0 Day 1 and Level 1 Day 3

18. Differential Incremental Backup Strategy
Consistent backup set size and backup duration
Slower recovery using more backup sets
Level 0 Differential Incremental (Full) - Day 1
Level 1 Differential Incremental - Day 2
Level 1 Differential Incremental - Day 3
Restorable to Day 1
All blocks backed up
Restorable to Day 2 using Level 0 Day 1 and Level 1 Day 2
Contains only blocks changed since Level 0 on Day 1
Restorable to Day 3 using Level 0 Day 1 and Level 1 Day2 and Level 1 Day 3
Contains only blocks changed since Level 1 on Day 2

19. Mixed Incremental Strategy
Monthly Full Level 0 Incremental backup
Weekly Level 1 Cumulative Incremental backup
Daily Level 1 Differential Incremental backup
Advantages
RMAN doesn’t have to apply more than a few days worth of differential backups to the latest cumulative backup and the original level 0 backup
No more than 1 day of redo logs need to be applied during recovery
Disadvantages
May not meet with your MTTR target (Mean-Time-to-Recovery)
Rule of Thumb:
You should perform a new Level 0 backup
once >50% of blocks have changed

20. Channel Parallelism in RMAN
Allocating multiple channels for a device type allows parallel completion of RMAN tasks
Manual channel allocation has to happen inside a RUN { } block
Device types can be configured for automatic allocation of parallel channels
CONFIGURE DEVICE TYPE DISK PARALLELISM 2;
Multiple channels can be used to write to multiple devices simultaneously
If a channel fails, surviving channels will attempt to complete the restore job
RUN { ALLOCATE CHANNEL c1 DEVICE TYPE sbt; ALLOCATE CHANNEL c2 DEVICE TYPE sbt; ALLOCATE CHANNEL c3 DEVICE TYPE sbt; BACKUP DATAFILE 5,6,7; }

21. RMAN Restore and Recovery

22. Database Recovery Procedure
Two Steps:
RESTORE
Missing files are restored from the blocks in backup sets OR
Image copies are copied to the original (or new) file locations
Unmodified files not modified can be skipped by RMAN automatically
RMAN uses the record of available backups in the RMAN repository to select the best available backups for use in the restore operation.
The most recent backup available, or the most recent backup satisfying any UNTIL clause specified in the RESTORE command, is always the preferred choice
If two backups are from the same point in time, RMAN prefers image copies over backup sets because RMAN image copy restores are faster
RECOVER
Recovery must be performed for incomplete backups
Archive logs are applied to the database

23. Reusing RMAN Procedures

24. RMAN scripting script Reusable lists of RMAN commands
Stored on the file system or in the RMAN respository
Not the Control file!
LOCAL scripts used by a single database instance
script
GLOBAL scripts shared by database instances in repository
# create recovery catalog script to back up database and archived logs
CREATE SCRIPT backup_whole
COMMENT "backup whole database and logs" {
BACKUP INCREMENTAL LEVEL 0 TAG b_whole_l0
DATABASE PLUS ARCHIVELOG; }
# creates recovery catalog script to back up database and archived logs CREATE GLOBAL SCRIPT global_backup_db
COMMENT "backup any database from the recovery catalog, with logs" {
BACKUP DATABASE PLUS ARCHIVELOG; }

25. Useful RMAN commands host
Execute a command on the local host from within RMAN
host
host “dd if=/orabak/tools.dbf of=/oradata/tools.dbf”

26. Useful RMAN commands sql
Execute a SQL command on the Target database within RMAN
sql
sql ‘alter system archive log current’;
Select statements not supported

27. Managing RMAN backups
list / report
crosscheck
validate
delete

28. Managing RMAN backups list / report
List all backup sets and pieces known by RMAN
May not represent actual files available on disk
list / report
LIST BACKUP OF DATABASE ARCHIVELOG ALL; # lists known backups of db files and logs LIST COPY; # lists only image copies LIST BACKUP; # lists all RMAN backup media
REPORT NEED BACKUP; # report which database files need backup

29. Managing RMAN backups crosscheck
Verifies existence of known backup file sets and pieces in the RMAN repository
Marks backup file sets and pieces as expired if they exceed retention policies
crosscheck
CROSSCHECK doesn’t physically delete anything!
CROSSCHECK BACKUPSET; # crosschecks backup sets on disk and SBT
CROSSCHECK BACKUP; # crosscheck all RMAN backup media
RMAN backup files have four possible states in the repository
AVAILABLE
UNAVAILABLE
EXPIRED
OBSOLETE

30. Managing RMAN backups validate
Verifies existence and availability of database file media
Checks for corrupted blocks and reports them in V$DATABASE_BLOCK_CORRUPTION
validate
Damaged backup file media may be repaired using Block Media Recovery
BACKUP VALIDATE DATABASE ARCHIVELOG ALL;
RESTORE CONTROLFILE VALIDATE;
RESTORE ARCHIVELOG ALL VALIDATE;
RESTORE DATAFILE 4,5,6 VALIDATE;

31. Managing RMAN backups delete
Remove any or all database backup file media from disk/tape and RMAN repository
Can remove obsolete media no longer needed to recover under retention policies
delete
DELETE BACKUP TAG='before_upgrade'; # delete backup based on tag
DELETE NOPROMPT ARCHIVELOG ALL; # delete all archivelogs
DELETE EXPIRED BACKUP; # delete expired after crosscheck
DELETE BACKUP; # delete ALL backups

32. RMAN Web Management in Grid Control

33. Jump in and use RMAN!
It is easier to show RMAN (and not just talk about it endlessly …)
rman target
rman
rman>> connect target
rman target catalog
rman target catalog auxiliary

34. Simple database backup
backup database;
Uses default device type setting (SBT or Disk)
Creates device channels according to parallelism setting
Creates image copies or backup sets
Might not backup controlfile automatically!
Doesn’t backup archivelogs

35. Inconsistent database backup including archive logs

36. show controlfile autobackup configure controlfile autobackup on
How do I ensure the controlfile is always backed up?
show controlfile autobackup configure controlfile autobackup on

37. Configuration Parameters
Setting and clearing
Configuration Parameters
show {parameter|ALL} configure {parameter} clear configure {parameter} {newsetting}

38. Restore and Recover
restore and recover

39. RMAN 11g Features RMAN 11g Features
Parallel backup of ‘regions’ of BIG datafiles
New encryption algorithm
Data Recovery Advisor 11g
Online backup of standby databases
Virtual, secure and mergeable RMAN catalogs
Encrypted disk backup sets
RMAN 11g Features

40. Thanks for your attention!

41. References
Oracle® Database Backup and Recovery Basics 10g Release 2 (10.2)
Oracle® Database Backup and Recovery Advanced User's Guide 10g Release 2 (10.2)
Oracle® Database Backup and Recovery Reference 10g Release 2 (10.2)
Freeman & Hart, Oracle9i RMAN Backup & Recovery, Oracle Press
(useful 3rd party media manager chapters)