Transcript Backup & Recovery with RMAN

Backup & Recovery with RMAN
LCG 3D Workshop, Bologna
June 12th, 2007
Jacek Wojcieszuk
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LCG
Agenda
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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
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• 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 within
assumed 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?
DBWR
Db file
LGWR
RedoLog
RedoLog
Log archiver
Db file
Db file
Db file
Backup proc.
Server proc.
SGA
Tapes
or
disks
system
Archived redo logs
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RMAN architecture
Target
Database
RMAN Client
Target
Database
Target
Database
Auxiliary
Database
RMAN
Catalog
Schema
Catalog
Database
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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
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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 recovery
operations
– 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 the
box
– 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 Media
Managers
– 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 Management
software 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
Recommended
Controlfile 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 backup
as copy of the whole database + incremental
backups used to update the copy + archived
redo 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 days
of 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 the
backups
• 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 logical
database force format '%d_%T_%U_lvl0T'
plus archivelog format '%d_%T_%U_lvl0Tarch';
delete noprompt force archivelog all completed before „sysdate - 2";
}
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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’;
}
LCG 3D Workshop, Bologna, June 2007 - 16
Backup operations at Tier0 (2)
run {
backup tag ‘some_tag_AR' archivelog all
format '%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 level
1 for recover of copy with tag ‘DB_Copy_tag’ database;
recover device type disk copy of database with tag DB_Copy_tag until time
‘sysdate -2 ‘;
delete force noprompt backupset device type disk tag DB_Copy_tag completed
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 it’s lost)
– Datafile restore from a backup
– Database recovery using incremental backups and/or
archived redo logs and online redo logs
startup mount
run {
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 implementing
SAME 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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set dbid=xxxxxxx
startup 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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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;
}
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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
ORA-01578: ORACLE data block corrupted (file # 19, block # 44)
ORA-01110: data file 19: ‘d:\oracle\oradata\data\mydb_maintbs_01.dbf’
run {
allocate channel c1 device type disk|sbt;
blockrecover datafile 19 block 44;
}
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Single/multiple
datafile/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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Hands on preparation
• https://twiki.cern.ch/twiki/bin/view/PSSGroup
/HandsOnExercises
• Please start a full backup of your database,
if possible use a tape system
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More info
• Oracle Database 10g RMAN
Backup & Recovery (by
Mathew Hart and Robert G.
Freeman)
• Oracle Documentation
– Backup and Recovery Basics
– Backup and Recovery
Advanced User's Guide
– Backup and Recovery
Reference
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