intro to rman

8/6/2019 Intro to RMAN

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Oracles Backup and Recovery Tool

Recovery MANager


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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

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RMAN can create imagecopiesusable by user-scripted restore procedures

RMAN can create backupsetsinstead of traditional image copies

RMAN uses disk or tape channels to read and write to disk or tape media

Exact c i s f targ t ata as fil s

RMAN rmits r starta l acku s if y u hav a s cific tim win w within

which acku s ar rmitt

RMAN ta vic s r ly n 3r

arty M ia Manag r s ftwar

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RMAN has a c mman -lin int rfac (rman) an is als int grat with Gri C ntr l


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Backup set media options

Backup Sets are logical groupings of backed-up database files

Backup sets can be written to disk or tapeBackup sets can be compressed by omitting unchanged blocks

Tape backup sets can be encrypted (via Oracle Secure Backup)

Tape backups mustuse backup sets

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Backup sets have a unique ID and may have a TAG for RMAN identification

Backup sets consist of one or more individual files called backuppieces.

Backup piece files contain the data blocksfrom a backup

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 Sets


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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

RUN {

ALLOCATE CHANNEL c1 DEVICE TYPE sbt;

BACKUP DATABASE PLUS ARCHIVELOG;

}

BACKUP DATAFILE 3;

RESTORE TABLESPACE users;

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Two types of device type disk and sbt

RMAN has an open AP

I for communicatingwith Tape and other media manager

software

RMAN sends labeled streams of bytes to the

media manager during backup

The labeled streams are returned by themedia manager during RMAN restore

operations

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;

Media Manager vendors have specific

installation instructions that vary by vendor

Refer to vendors for detailed installation

and use instructions

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Backup Set

ImageCopy

RMAN-proprietary storage of backed-up data blocks

Consist of a Backup Set identifier plus associated backup set files or pieces

Can only be restoredusing RMAN

Equivalent to file copies of original database files

RMAN considers user-managed backups as Image Copies

ContainALL data blocks no compression

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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 COPY OF DATABASE FROMTAG=full_cold_copy TAG=new_full_cold_copy;

BACKUP AS COPY DATABASE TAG=full_cold_copy;

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Full backup

Incremental backup

Backup ofallspecified database file blocks

Independent of when database files were last backed up

Not used in incremental backup strategies

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

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Level 0 incremental backups

Backup ofallblocks in specified database files

Independent of when files were last backed up

Base for subsequent Level 1 backups

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Differential backup

Contain all blocks changed after the most

recent incremental backup at level 1 or 0

Level 1 incremental backups

Cumulative backup

Contain all blocks changed after the most

recent incremental backup at level 0Cumulative backups become much larger over time

Cumulative backups are quicker to restore

Differential backups remain smaller and quicker to perform

Differential backups are slower to restore requiring changes

in multiple earlier incremental backups

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RMAN can use a Block Change Tracking file to identify changed blocks

RMAN can report, validate, remove or protect backup files

RMAN can throttle disk I/O rate during backup and restore

RMAN can limit the number and size of backup set files

RMAN performance controls

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

RMAN will create a missing Level 0 backup automatically when

asked to perform a Level 1 backup

RMAN and missing Level 0 backups

Change Tracking file can introduce database overhead

you need to evaluate if it is worth the extra performance hit

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RMAN can backup and restore your Flash Recovery Area

RMAN can use and manage ASM files

RMAN can clone (duplicate) databases using the AUXILIARY connection

RMAN can switch an instance to use a copyof a database or datafiles

RMAN actions can be scripted and scheduled using cron or dbms_job

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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 cant share a repository!

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Level 0 CumulativeIncremental (Full) - Day 1

Level 1 CumulativeIncremental - Day2

Level 1 CumulativeIncremental - Day 3

All blocks backed up

Restorable to Day 1

Contains only blocks changed sinceLevel 0 on Day 1

Restorable to Day 2 using Level 0 Day1 and Level 1 Day 2

Contains only blocks changed since

Level 0 on Day 1Restorable to Day 3 using Level 0 Day1 and Level 1 Day 3

Increasing backup set size and backup duration

Faster recovery

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Level 0 DifferentialIncremental (Full) - Day 1

Level 1 DifferentialIncremental - Day 2

Level 1 DifferentialIncremental - Day 3

ll l cks acke u

est ra le t Day 1

C ntains nly l cks change sinceLevel 0 n Day 1

est ra le t Day 2 using Level 0 Day1 an Level 1 Day 2

C ntains nly l cks change sinceLevel 1 n Day 2

est ra le t Day 3 using Level 0 Day1 an Level 1 Day2 an Level 1 Day 3

C nsistent acku set size an acku urati n

Sl wer rec very using m re acku sets

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C. Daily Level 1 Differential Incremental backup

A. Monthly Full Level 0 Incremental backup

B. Weekly Level 1 Cumulative Incremental backup

Advantages

RMAN doesnt 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)

RuleofThumb:

You should perform a new Level 0 backup

once >50% of blocks have changed

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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{




BACKUP DATAFILE 5,6,7;

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Two Steps:

RESTORE

RECOVER

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

Recovery must be performed for incomplete backups

Archive logs are applied to the database

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

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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

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

CREATEGLOBAL SCRIPT global_backup_db

COMMENT "backup any database from the recovery catalog, with logs"

{ BACKUP DATABASE PLUS ARCHIVELOG;

}

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host

Execute a command on the local host from within RMAN

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

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sql

Execute a SQL command on the Target database within RMAN

sql alter system archive log current;

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Select statements not supported


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list / report

crosscheckvalidate

delete

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list / reportLIST 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

List all backup sets and pieces known by RMAN

May not represent actual files available on disk

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crosscheckCROSSCHECK BACKUPSET; # crosschecks backup sets on disk and SBT

CROSSCHECK BACKUP; # crosscheck all RMAN backup media

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 doesnt physically delete anything!

RMAN backup files have four possible states in the repositoryAVAILABLE

UNAVAILABLE

EXPIRED

OBSOLETE

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validateBACKUP VALIDATE DATABASE ARCHIVELOG ALL;

RESTORE CONTROLFILE VALIDATE;

RESTORE ARCHIVELOG ALL VALIDATE;

RESTORE DATAFILE 4,5,6 VALIDATE;

Verifies existence and availability of database file media

Checks for corrupted blocks and reports them in

V$DATABASE_BLOCK_CORRUPTION

Damaged backup file media maybe repaired using Block

Media Recovery

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deleteDELETE 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; # deleteALL backups

Remove any or all database backup file media from disk/tapeand RMAN repository

Can remove obsolete media no longer needed to recover

under retention policies

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

rman target system/pswd@sid1

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

rman target system/pswd@sid1 catalog rman/pswd@rmansid auxiliary system/pswd@sid2

rman

rman>> connect target system/pswd@sid1

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backupdatabase;

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!

Doesnt backup archivelogs


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Inconsistentdatabase backupincluding

archivelogs


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show controlfileautobackup

configurecontrolfileautobackupon


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show {parameter|ALL}

configure {parameter}clear

configure {parameter} {newsetting}


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restoreand recover


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RMAN 11gFeatures

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


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OracleDatabaseBackupandRecovery Basics10g Release 2 (10.2)http://download.oracle.com/docs/cd/B19306_01/backup.102/b14192/bkup004.htm#sthref385

OracleDatabaseBackupandRecovery Advanced User'sGuide 10g Release 2 (10.2)http://download-east.oracle.com/docs/cd/B14117_01/server.101/b10734/toc.htm

OracleDatabaseBackupandRecovery Reference10g Release 2 (10.2)http://download-west.oracle.com/docs/cd/B19306_01/backup.102/b14194/toc.htm

Freeman & Hart, Oracle9iRMANBackup & Recovery,Oracle Press

(useful 3rd party mediamanager chapters)http://www.mhprofessional.com/product.php?cat=7&isbn=0072226625

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intro to rman

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