60009953 backup recovery with rman

8/3/2019 60009953 Backup Recovery With RMAN

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ERN - IT Department

CH-1211 Genve 23Switzerlandwww.cern.ch/i t

Backup & Recovery with RMAN

LCG 3D Workshop, BolognaJune 12 th , 2007

Jacek Wojcieszuk

LCG


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ERN - IT Department

CH-1211 Genve 23Switzerlandwww.cern.ch/i t LCG 3D Workshop, Bologna, June 2007 - 2

Agenda

Types of failures and backups in Oracle RMAN Architecture Manual vs. RMAN backups On-tape backups with RMAN

RMAN Configuration RMAN backup strategies RMAN backups at Tier0 Exemplary recovery scanarios

Demo


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Types of failures

Instance Failure Usually connected with an Oracle process failure

Media Failure Disk failure, storage array controller failure etc.

Block Corruption Usually caused by bugs in Oracle software Human error

In most cases accidentally deleted/updated data

Database user or DBA Disaster

Fire, flood, earthquake, plane crash etc.


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Backup options in Oracle

Physical backups Cold (off-line) backups

Full database only Require downtime Do not provide flexibility for point in time recovery (PiTR)

Hot (on-line) backups Different types of backups: full, incr. (cumulative, differential),

archivelogs Different scopes: full database, tablespace(s) or datafile(s) Do not require database downtime Can be used to recover full database, single/multiple

tablespace(s)/datafile(s) or a corrupted block Database can be recovered to any point in time withinassumed backup retention period


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Backup options in Oracle (2)

Logical backups Logical copy of data in the database Support for different backup granularity Can be taken either with legacy Export/Import

tools or with Data Pump (10g)

Standby systems (Data Guard) Physical and logical standby databases


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How hot backups are possible?

SGA

S er v

er

pr o

c.

DBWR LGWR

RedoLog

RedoLog

Db

fileDb

fileDb

fileDb f

ile

L o g ar ch i v

er

Archived redo logs

B

a ck

u p pr o

c.

Tapesor

diskssystem


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RMAN architecture

TargetDatabase

RMAN Client

TargetDatabase

TargetDatabase

AuxiliaryDatabase

RMANCatalogSchema

CatalogDatabase


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Switzerlandwww.cern.ch/i t LCG 3D Workshop, Bologna, June 2007 - 8

Types of RMAN hot backups Copy or backupset Full database backup

Incremental backups (in 10g 2 levels available: 0 and 1) Cumulative, differential Can be used to update a copy of the database

Archivelog backups Tablespace(s), datafile(s) backups

Differential incremental Cumulative incremental


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Manual vs. RMAN backups

RMAN advantages: Supports incremental backup strategies RMAN on-line backups are not so heavy for the system as

manual on-line backups RMAN can detect corrupted blocks RMAN automatically track database structure changes

Provides easy, automated backup, restore and recoveryoperations Keeps invenotory of taken backups Can seamlessly work with third party media managers

Disadvantage: something new to learn RMAN concepts and command syntax sometimes are not

intuitive


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On-tape backups with RMAN

RMAN allows to take on-disk backups out of thebox Flash recovery area, if configured, further simplifies such

backups On disk backups are interesting but usually not sufficient

for a disaster recovery

On-disk backups can be manually sent to tapes Recovery can be very troublesome

RMAN can seamlessly work with third party MediaManagers Media Manager Library (MML) is required Different configuration tasks for different MMLs


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On-tape backups with RMAN (2)

Many vendors of Media Managementsoftware provide MMLs

Most popular are: Tivoli Storage Manager

Veritas NetBackup EMC NetWorker

Oracle Secure Backup Very new and probably not yet reliable enough


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RMAN Configuration

RMAN can be preconfigured

Configuration is stored in the control file and in the recovery catalog(if used) Can facilitate backup automation

Most useful settings:

Setting Default RecommendedControlfile autobackup off on

Retention policy to redundancy 1 to recovery window of 31 days

Device type disk parallelism 1 ... disk|sbt prallelism 2 ...

Default device type to disk to sbt

Backup optimization off off

Channel device type none sbt parms=...

Maxsetsize unlimited depends on your database size


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RMAN Configuration (2)

Example:

configure RETENTION POLICY TO RECOVERY WINDOW OF 31 DAYS;configure DEFAULT DEVICE TYPE TO 'sbt';configure DEVICE TYPE 'sbt' PARALLELISM 2;configure CHANNEL DEVICE TYPE sbt parms='ENV=

(TDPO_OPTFILE=/opt/tivoli/tsm/client/oracle/bin/tdpo.opt)';

configure DEVICE TYPE DISK PARALLELISM 2;configure MAXSETSIZE TO 200 G;configure archivelog backup copies for device type 'sbt' to 1;configure controlfile autobackup on;

The SHOW ALL command lists all RMAN configuration

settings To clear a given settings append CLEAR at the end of the CONFIGURE command


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RMAN backup strategies

RMAN allows many types of backups It possible to build own backup strategy that

suits given database best There are also Oracle recommended

backup strategies: Incremental backup strategy: level 0 backups +

level 1 backups (cumulative and/or differential)and archivelog backups inbetween.

Incrementally updated database copy: 1 backupas copy of the whole database + incrementalbackups used to update the copy + archivedredo logs.


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Backup strategy used at Tier0

Both Oracle-recommended strategies implemented

for all production systems Incremental backup strategy:

Backups go to tapes Weekly or biweekly level 0 backups (depending on the DB

size) A level 1 cumulative backup inbetween Daily incremental level 1 differential backups Archivelog backup every 30 minutes

Incrementally updated DB copy strategy:

daily incremental differential backups applied with 2 daysof delay Copies, incremental backups and archived redo logs

stored in the Flash Recovery Area


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Backup operations at Tier0

Central machine to schedule and run all thebackups

Central RMAN catalog exported on regular basis Examples of RMAN commands being used:

run {crosscheck archivelog all;

backup force tag some_tag _0T' incremental level 0 check logicaldatabase force format '%d_%T_%U_lvl0T'plus archivelog format '%d_%T_%U_lvl0Tarch';

delete noprompt force archivelog all completed before sysdate - 2";}

run {crosscheck archivelog all;backup tag some_tag _1D' incremental level 1

database format '%d_%T_%U_lvl1D'plus archivelog format '%d_%T_%U_lvl1Darch';

delete noprompt force archivelog all completed before sysdate 2;}


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Backup operations at Tier0 (2)

run {backup tag some_tag _AR' archivelog allformat '%d_%T_%U_arch';delete noprompt force archivelog all completed before sysdate - 2;}

run {backup maxsetsize 2047G tag ' DB_Copy_tag' device type disk incremental level1 for recover of copy with tag DB_Copy_tag database;

recover device type disk copy of database with tag DB_Copy_tag until timesysdate -2 ;

delete force noprompt backupset device type disk tag DB_Copy_tagcompleted before sysdate -2;

}


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Complete database recovery

Needed when: All datafiles are lost or the SYSTEM tablespace datafiles

are lost At least one member of each redo log group survived

Requires: Control file recovery (if its lost) Datafile restore from a backup Database recovery using incremental backups and/or

archived redo logs and online redo logs

startup mountrun {allocate channel c1 device type disk|sbt;allocate channel c2 device type disk|sbt;restore database check readonly;recover database;alter database open;

}


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Database point-in-time recovery

Needed when: all datafiles are lost All copies of the current control file are lost Or all online redo log group members are lost

The most typical recovery in case of systems implementingSAME approach

If done after a disaster it has to be preceded by: Hardware configuration OS and Oracle software installation Re-creation or restore from non-RMAN backup of listener.ora,

tnsnames.ora and other important configuration files ASM instance and diskgroup configuration (if needed) MML installation and configuration ...

Requires Spfile restore Controlfile restore Datafiles restore and recovery


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run {set until time = "to_date('24-AUG-2006 00:00:00','dd-mon-yyyy hh24:mi:ss')";allocate channel c1 device type disk|sbt;allocate channel c2 device type disk|sbt;restore database check readonly;recover database;alter database open resetlogs;

}

set dbid=xxxxxxxstartup nomount;run {allocate channel c1 device type disk|sbt;restore spfile to some_location from autobackup;recover database;alter database open resetlogs;}shutdown immediate;

startup nomount;run {allocate channel c1 device type disk|sbt;restore controlfile from autobackup;alter database mount;}


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Tablespace point-in-time recovery

Needed Mainly to address a human error

Oracle makes efforts to automate it Can be done with few clicks in OEM

Requires Point in time recovery of the whole database (an

auxiliary instance is created) Export/import of selected tablespaces schemas

or objects


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Block media recovery

Needed when:

Database reports either single or multi block corruption Can be done with an open database Only the table(s) containing corrupted blocks are not

available Database corruptions can be discovered with RMAN

backup validate database command Corrupted blocks can be found in

V$DATABASE_BLOCK_CORRUPTION

run {allocate channel c1 device type disk|sbt;blockrecover datafile 19 block 44;}

ORA-01578: ORACLE data block corrupted (file # 19, block # 44)

ORA-01110: data file 19: d:\oracle\oradata\data\mydb_maintbs_01.dbf


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Single/multipledatafile/tablespace recovery Needed when

Single/multiple tablespaces or datafiles have been lost SYSTEM tablespace is intact Controlfiles and online redo logs are intact

Requires To put offline datafiles and tablespaces being recovered The database can be open and available to users

run {sql alter tablespace users offline;

allocate channel c1 device type disk|sbt;restore tablespace users;recover tablespace users;sql alter tablespace users online;

}


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Demo


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Switzerlandh/i

More info

Oracle Database 10g RMAN

Backup & Recovery ( byMathew Hart and Robert G.Freeman)

Oracle Documentation Backup and Recovery Basics Backup and Recovery

Advanced User's Guide Backup and Recovery

Reference

60009953 backup recovery with rman

Documents