Lesson 19 Introduction to RMAN

• A hands-on introduction to RMAN. You will learn what it is and how to make use of basic, critical backup and recovery techniques.

Lesson Objectives

• Introduction to RMAN
• RMAN Components
• Starting and connecting to RMAN
• Basic Operations: Backup
• Basic Operations: Restore, Recover
• Workshop

What is RMAN?...

• Oracle utility for backup, restore and recovery
• Provides server-managed recovery
• Can be used in place of OS copy (user-managed) backup techniques
  • Automates many tasks
  • Considered easier than user-managed backups?
• Shipped with all versions of Oracle

...What is RMAN?

• Extra cost
  • Base software - $0
  • Tape (media manager) software
    • Limited feature version free from Legato
    • Purchase from Legato or Veritas – Big $$$
  • Training - ???
• Supports Oracle 8 and up
  • Cannot use with version 7 databases
• Command line execution or Graphical UI through Oracle Enterprise Manager

RMAN Components

• RMAN executable
  • Client application
  • Can run on entirely separate machine
  • Starts server sessions on Target Database
• Target Database
  • Database to be backed up
• RMAN repository
  • Automatic and not optional
  • In target database control file
  • Optionally also in separate database
    • Create a “recovery catalog”
    • Keeps complete history of backup and recovery operations

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RMAN Components

• Media Management Library
  • Required only if backing up to tape
  • Communicates with server session on target database
  • Reads and Writes to tape

Starting and Connecting...

• Start RMAN from the OS command prompt

...Starting and Connecting

• Start RMAN without parameters
• More secure
• Prevents snooping password with Unix "ps" command

Common RMAN Commands...

• BACKUP
• RESTORE
• RECOVER
• ALLOCATE CHANNEL
• CONFIGURE
• SHOW

...Common RMAN Commands

• REPORT (on target database)
• LIST (backup set info)
• STARTUP, SHUTDOWN
• ALTER DATABASE
• SQL 'sql statement'
• HOST 'os command'

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Backup Concepts...

• The BACKUP command is used to backup
  • Read entire datafile, writes to specified location
  • Creates one or more backup sets
  • Remembers name and location of sets
• Each channel creates at least one backup set
  • Backupset is the unit of restart
  • Start multiple channels and/or use FILESPERSET to create multiple sets
    • Also see MAXSETSIZE configuration

...Backup Concepts

• Backup set contains 1 or more pieces
  • Backup piece = OS file
  • Contains backed up blocks
  • Proprietary format
  • Can only restore with RMAN RESTORE
• Database must be either mounted or open
  • Exception: NOARCHIVELOG database must be mounted (not open)

Full Backup...

• Easy to do full backup of all datafiles, control file and archive logs
• All ever used blocks in datafile are backed up
  • Exception: Skips TEMP tablespace
• Skips datafile blocks never used - compression
• The database can be mounted or open
  • RMAN detects fractured blocks - auto reread
  • No need for Hot backup mode

...Full Backup

Full Tablespace Backup

• Full backup by tablespace
• All blocks ever used are copied to backup

Datafile Backup

• BACKUP command supports one or more datafile names:

Incremental Backup...

• Incremental backup backs up only changed blocks
  • Changed since the last incremental or cumulative backup
• Potentially much less data written to backup!
  • Save lots of space
• Implemented with a multiple “level” scheme
  • Level 0 backs up ALL blocks
  • Level 1 backs up only blocks changed since last 0 or 1

...Incremental Backup

• Sunday start with level 0:
• Monday, Tues, Wed follow with a higher level

Backups – Where to go from here

• Look into:
  • Cumulative Incremental
  • Image Copy
  • Tuning
  • Planning
  • Backing up to tape – installing the MML
  • Monitoring with V$SESSION_LONGOPS, V$SESSION_WAIT
  • Metalink Doc ID Note:120084.1

RESTORE Command

• Restore datafiles, control files & archive logs
• Restores to original location by default
  • Will overwrite files w/o warning
• Source: backup sets or image copies
• Will not restore if not needed
  • Checks location and datafile header
  • Does not check for block corruption
  • Use FORCE to override

RECOVER Command

• RECOVER Command
  • Apply logs or incremental backups to restored file
  • Complete recovery
    • Up to last commit
  • Incomplete recovery
    • Up to specified time, SCN or log sequence number
    • See the “SET UNTIL” command

Complete Recovery – Database

• Scenario:
  • Recovering all datafiles to most current time, original location
  • Control file available, database mounted, not open

Recover Tablespace...

• Scenario:
  • Recovering one tablespace to most current time, original location
  • Control file available
  • Database can be open, tablespace offline
• Determine which tablespace this file is in:

...Recover Tablespace...

• Restore and recover tablespace
  • RMAN knows what and where the latest backup is

...Recover Tablespace

• Can use SET NEWNAME to restore to a new location:

Summary: Restore and Recovery

• Study other scenarios:
  • Point-in-Time (PIT) recovery
  • Recovering the control file
  • Tablespace PIT recoveries
  • Block-Level recovery

Reporting

• Ways of accessing metadata:
  • REPORT command
    • Report on backups taken, backups needed
  • LIST command
    • Report on files such as backup sets and image copies
  • SHOW command
    • Display CONFIGURE command settings
  • SELECT from Recovery Catalog views

Report Need Backup

Show Stored Settings

What Else is There?

• Setting up and using a separate catalog database
• Backing up to tape
• Tuning RMAN
• Duplicating databases for testing
• Creating Standby Databases
• Real Application Cluster support

Getting More Information

• Text book
  • Oracle9i RMAN Backup and Recovery
  • Freeman, Hart
  • ISBN 0-07-222662-5
• Metalink
• Oracle documentation

RMAN Workshop

• RMAN