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Agenda

RMAN Architecture Why Use RMAN? Implementation Decisions RMAN Oracle9i New Features

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RMAN Architecture

Recovery Manager (RMAN) is a tool that can be used for Backup, Restore, and Recovery operations on your target database

Standard utility when installing Oracle binaries

• No extra license required• Only works on 8.0 or higher• Some features only implemented if using Enterprise

Edition

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RMAN Architecture (continued)

TargetDatabasedatafiles

controlfiles

Archived redo logs

rman

ServerProcesses Recovery

CatalogDatabase(optional)

Backup fileson disk

ServerProcesses

ServerProcesses

MediaManagement

(optional)

Backupmedia

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RMAN Architecture (continued)

Target Database• Database to be backed up, restored,or recovered• Datafiles, controlfies, archived redo files are backed

up

rman executable• Utility you invoke for backup, restore, and recovery

operations

Processes and Channels• RMAN uses processes to communicate with target

and catalog databases• A process opened for I/O is called a channel

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RMAN Architecture (continued)

Backups, Backup Sets, Backup Pieces• Backups are made up of Backup Sets• Backup Sets are made up of Backup Pieces• Backup pieces are the physical backup files• rman is only utility that can read/write from physical

files

Target database control files• Contain information about RMAN backup operations• SQL> alter session set events ‘immediate trace

name controlf level 10’; Backup sets, pieces, datafiles Configuration settings (Oracle9i only)

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RMAN Architecture (continued)

What’s the Catalog Database?• A separate database usually on a separate host from

target database• Schema that has objects that store data about

backup, restore, and recovery activities

Catalog Database (optional)• Optional because much of same meta data in

catalog is always stored in the target control file

Catalog does not contain backup files

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RMAN Architecture (continued)

Media Management Layer (MML)• 3rd party piece of software• Tracks what files have been written to

what tapes• MML required if backing up files to tape• Optional because you can take backup

directly to disk• Can be frustrating to setup

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So Why Use RMAN?

Incremental backups• Full will backup only used blocks• Incremental scheme to back up

changed blocks• Backup resources correlate to

transaction activity and not the size of the database

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RMAN Advantages (continued)

Tablespaces not put in backup mode• No extra logging of full blocks to

online redo logs during backup• With RMAN a database process is

doing the copy• RMAN does a head/tail check on

each block

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RMAN Advantages (continued)

Automatic checking for corruption• Database block• Archived redo log

RMAN reads every block and checks for corruption

Corrupt blocks information logged• v$backup_corruption• v$copy_corruption

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RMAN Advantages (continued)

Configurable I/O characteristics• Configure multiple I/O channels to

process in parallel backup and restore commands

• Set max file size• Set max read rate

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RMAN Advantages (continued)

Logging of all backup operations• RMAN writes what/when/where to

target controlfile (and catalog if using)• Listing and reporting commands

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Implementation Decisions

Backup to disk (no MML required) Backup to tape (must use MML) Use RMAN with catalog Use RMAN without catalog

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Most Moving Parts

TargetDatabasedatafiles

controlfiles

Archived redo logs

rman

ServerProcesses Recovery

CatalogDatabase

ServerProcesses

ServerProcesses

MMLBackupmedia

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Simplest Implementation

Target

Databasedatafiles

controlfiles

Archived redo logs

rman

ServerProcesses

Backup fileson disk

ServerProcesses

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Disk Based Backup

Set channel type disk Let O/S backup scrape files to tape Sometime after O/S backup delete

RMAN backup files from disk Advantages of Disk

• Easier to setup (no MML)• Fewer moving parts• Disk access faster

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Disk Based Backup (continued)

Disadvantages of Disk• If RMAN backup file has been deleted

from disk, and if needed during a restore, DBA has to tell Operator which file needs to be retrieved and what day it was backed up

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Tape Based Backup

Configure RMAN to backup to tape • Implement MML• Set channel type sbt_tape

Advantages of Tape• Tape storage is cheaper than disk• Might be only option for a large database• MML keeps track of long history of what file

is on what tape

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Tape Based Backup (continued)

Disadvantages of Tape• MML setup can be frustrating• And MML adds complexity

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Why Use a Catalog?

Gives you more flexibility in certain situations

Oracle8i reasons to use a catalog•Restoring controlfile•Marking backup sets unavailable•Listing commands

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Why Use a Catalog? (continued) 8i and 9i Reasons to Use Catalog

• One centralized repository for all your target databases

If not using catalog, finite amount of days of RMAN backup operations stored• control_file_record_keep_time has a default of 7

days• Could be an issue for a database with hundreds

of datafiles With catalog you can store data for long

periods of time

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Catalog Disadvantages

Another moving part Another database to maintain,

monitor, backup, etc. Can get complex if many different

versions of targets• One catalog, one schema• One catalog, multiple schemas• Different catalogs

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If Not Using a Catalog

May need to increase init.ora control_file_record_keep_time

In 8i, ensure that you backup your controlfile outside of RMAN

SQL> alter database backup controlfile to ‘<path>/<filename>’;

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RMAN 9i New Features

RESTORE command optimized Block level recovery New ways to handle archived redo Configurable Persistent Settings

•Autobackup of controlfile•Optimization•I/O channel characteristics

Backup/Restore syntax simplified

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Oracle9i New Features Can easily give fellow DBA heart attack

• Pick a paranoid one Setup

• No Server Manager in Oracle9i• Create a file $ORACLE_HOME/bin/svrmgrl• chmod +x

echo “ “echo “SVRMGR> ORA-99999: deleting all datafiles…”sleep 2

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RMAN 9i New Features

RESTORE command optimized

RMAN restore now does:• Checks if file is on disk• Checks file header• If passes checks, does not restore

Can override w/FORCE option

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RMAN 9i New Features

Block Level Recovery Detecting block level corruption

•v$backup_corruption•trace files•dbverify

RMAN> blockrecover datafile 2 block 30;

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RMAN 9i New Features

Block Level Recovery (continued)• Appropriate for small amounts of

corruption• Could reduce mean time to recovery• Does not replace datafile

restore/recovery• Gives DBA another restore/recovery

tool

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RMAN 9i Archive Redo Backups New BACKUP … PLUS ARCHIVELOG

command

RMAN> backup database plus archivelog; 1. Switches online redo logs2. Backup archivelog all;3. Backs up files database datafiles4. Switches online redo logs5. Backs up any archived redo logs generated

during backup

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9i RMAN Controlfile Restore

New CONFIGURE command Settings stored in target controlfile Enable autobackup controlfile

RMAN> configure controlfile autobackup on;

Controlfile automatically backed up with BACKUP and COPY commands

RMAN controlfile restore can then be done without connecting to catalog

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RMAN 9i New Features (continued)

Configure optimization

RMAN> configure backup optimization on;

If a file has been backed up and hasn’t changed since last backup, RMAN will skip the file

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RMAN 9i New Features (continued)

Configure persistent channel I/O settings

Persist until you change or clear

RMAN> configure default device type to disk;RMAN> configure device type disk parallelism 2;RMAN> configure channel device type disk format

/ora01/brdstn/rman_%U.bus;

RMAN> show all;

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RMAN 9i New Features (continued)

Syntax simplified for BACKUP and RESTORE commands

No longer required to wrap within RUN{} command

Syntax now can be as simple as:

RMAN> backup database;RMAN> restore database;

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RMAN Summary

RMAN has significant advantages Many different ways to implement Enhancements to RMAN in Oracle9i Q&A