1. Backup & Recovery with RMAN

2. 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
LCG 3D Workshop, Bologna, June

3. LCG 3D Workshop, Bologna, June 2007 - 3
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.
LCG 3D Workshop, Bologna, June

4. 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 within assumed backup retention period
LCG 3D Workshop, Bologna, June

5. 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
LCG 3D Workshop, Bologna, June

6. How hot backups are possible?
Server proc.
Backup proc.
SGA
Tapes or
disks
system
DBWR
LGWR
Log archiver
RedoLog
Db file
Db file
Db file
Db file
RedoLog
Archived redo logs
LCG 3D Workshop, Bologna, June

7. LCG 3D Workshop, Bologna, June 2007 - 7
RMAN architecture
Target
Database
RMAN Client
Target
Database
RMAN
Catalog
Schema
Target
Database
Auxiliary
Database
Catalog Database
LCG 3D Workshop, Bologna, June

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
Cumulative incremental
Differential incremental
LCG 3D Workshop, Bologna, June

9. LCG 3D Workshop, Bologna, June 2007 - 9
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
LCG 3D Workshop, Bologna, June

10. 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
LCG 3D Workshop, Bologna, June

11. 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
LCG 3D Workshop, Bologna, June

12. LCG 3D Workshop, Bologna, June 2007 - 12
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
Channel device type
none
sbt parms=‘...’
Maxsetsize
unlimited
depends on your database size
LCG 3D Workshop, Bologna, June

13. LCG 3D Workshop, Bologna, June 2007 - 13
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
LCG 3D Workshop, Bologna, June

14. 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.
LCG 3D Workshop, Bologna, June

15. 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
LCG 3D Workshop, Bologna, June

16. 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"; }
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

17. 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’; }
LCG 3D Workshop, Bologna, June

18. 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; }
LCG 3D Workshop, Bologna, June

19. 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
LCG 3D Workshop, Bologna, June

20. LCG 3D Workshop, Bologna, June 2007 - 20
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;
run {
allocate channel c1 device type disk|sbt;
restore controlfile from autobackup;
alter database mount; }
run {
set until time = "to_date('24-AUG :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; }
LCG 3D Workshop, Bologna, June

21. 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
LCG 3D Workshop, Bologna, June

22. LCG 3D Workshop, Bologna, June 2007 - 22
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; }
LCG 3D Workshop, Bologna, June

23. 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”; }
LCG 3D Workshop, Bologna, June

24. LCG 3D Workshop, Bologna, June 2007 - 24
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
LCG 3D Workshop, Bologna, June