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Introduction to RMAN. Oracle’s Backup and Recovery Tool Recovery MANager. Introduction to RMAN. Oracle’s Backup and Recovery Tool Recovery MANager. Presented by Paul Hebert/ITEC. What RMAN does. RMAN creates backups and restores Oracle database files to tape or disk. Datafiles

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introduction to rman
Introduction to RMAN

Oracle’s Backup and Recovery Tool

Recovery MANager

introduction to rman2
Introduction to RMAN

Oracle’s Backup and Recovery Tool

Recovery MANager

Presented by Paul Hebert/ITEC

what rman does
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
other rman capabilities
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

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
rman channels
RMAN 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;

rman media managers
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
rman backup output media
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
rman tags
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;

rman backup types
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

incremental backup types
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
incremental backup types13
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
other rman capabilities14
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
other rman capabilities15
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

what doesn t rman do
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!
cumulative incremental backup strategy
Cumulative Incremental Backup Strategy

Increasing backup set size and backup duration

Faster recovery

differential incremental backup strategy
Differential Incremental Backup Strategy

Consistent backup set size and backup duration

Slower recovery using more backup sets

mixed incremental strategy
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
channel parallelism in rman
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;}

database recovery procedure
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
rman scripting
RMAN scripting
  • Reusable lists of RMAN commands
  • Stored on the file system or in the RMAN respository
  • Not the Control file!

script

  • LOCAL scripts used by a single database instance
  • 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;

}

useful rman commands
Useful RMAN commands

Execute a command on the local host from within RMAN

host

host “dd if=/orabak/tools.dbf of=/oradata/tools.dbf”

useful rman commands26
Useful RMAN commands

Execute a SQL command on the Target database within RMAN

sql

sql ‘alter system archive log current’;

Select statements not supported

managing rman backups
Managing RMAN backups

list / report

crosscheck

validate

delete

managing rman backups28
Managing RMAN backups

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 logsLIST COPY; # lists only image copiesLIST BACKUP; # lists all RMAN backup media

REPORT NEED BACKUP; # report which database files need backup

managing rman backups29
Managing RMAN backups

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

managing rman backups30
Managing RMAN backups

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;

managing rman backups31
Managing RMAN backups

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

jump in and use rman
Jump in and use RMAN!

It is easier to show RMAN (and not just talk about it endlessly …)

rman target system/pswd@sid1

rman

rman>> connect target system/pswd@sid1

rman target system/pswd@sid1 catalog rman/pswd@rmansid

rman target system/pswd@sid1 catalog rman/pswd@rmansidauxiliary system/pswd@sid2

backup database

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
slide38

Restore and Recover

restore and recover

rman 11g features

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
slide41

References

  • Oracle® Database Backup and Recovery Basics10g Release 2 (10.2) http://download.oracle.com/docs/cd/B19306_01/backup.102/b14192/bkup004.htm#sthref385
  • Oracle® Database Backup and Recovery Advanced User's Guide 10g Release 2 (10.2)

http://download-east.oracle.com/docs/cd/B14117_01/server.101/b10734/toc.htm

  • Oracle® Database Backup and Recovery Reference10g Release 2 (10.2)

http://download-west.oracle.com/docs/cd/B19306_01/backup.102/b14194/toc.htm

  • Freeman & Hart, Oracle9i RMAN Backup & Recovery, Oracle Press

(useful 3rd party media manager chapters)

http://www.mhprofessional.com/product.php?cat=7&isbn=0072226625