2 Copyright © 2007, Oracle. All rights reserved. Configuring for Recoverability.
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Transcript of 2 Copyright © 2007, Oracle. All rights reserved. Configuring for Recoverability.
2Copyright © 2007, Oracle. All rights reserved.
Configuring for Recoverability
Copyright © 2007, Oracle. All rights reserved.2 - 2
Objectives
After completing this lesson, you should be able to:• Invoke RMAN and set and list simple configurations• Configure your database in ARCHIVELOG mode• Configure multiple archive log file destinations to increase
availability• Specify a retention policy• Configure the Flash Recovery Area• Describe the benefits of using the Flash Recovery Area
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Purpose of Backup and Recovery Functionality
Backup and recovery functionality is needed for the following:• Data protection
– Media failure– User errors– Application errors
• Data preservation• Data transfer
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Typical Backup and Recovery Tasks
To be able to recover from data loss problems with minimal down time, you should be prepared to do the following:• Configure the database for recoverability.• Define a backup schedule.• Plan and test different types of failure scenarios.• Monitor and troubleshoot the backup and recovery
environment.• Restore data from backups.• Recover transactions to a desired point in time.
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Oracle Backup and Recovery Solutions
These Oracle utilities and features provide the tools necessary to maintain a recoverable system:• Recovery Manager (RMAN)
– Incremental backups– Block media recovery– Unused block compression– Binary compression– Backup encryption
• Data Pump
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Using Recovery Manager
$ rman target /
RMAN> BACKUP DATABASE;Starting backup at 10-JUN-07..RMAN> LIST BACKUP;BS Key Type LV Size Device Type Elapsed Time Completion Time------- ---- -- ------- ----------- ------------ ---------------1 Full 1.06G DISK 00:01:49 10-JUN-07..RMAN> DELETE OBSOLETE;..Do you really want to delete the above objects (enter YES or NO)? YESdeleted archived log..
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Types of RMAN Commands
RMAN commands are of the following types:• Stand-alone command:
– Is executed individually at the RMAN prompt– Cannot appear as subcommands within RUN
• Job command:– Must be within the braces of a RUN command– Is executed as a group
Some commands can be executed as either astand-alone or a job command.
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Job Commands: Example
Job commands appear inside a RUN command block:
RMAN> RUN2> {3> ALLOCATE CHANNEL c1 DEVICE TYPE DISK4> FORMAT "/disk2/%U";5> BACKUP AS BACKUPSET DATABASE;6> SQL 'alter system archive log current'; 7> }
Deallocated after theRUN block completes
Execution of entire block startswhen this line is entered.
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Configuring Your Database for Backup and Recovery Operations
• Operate the database in ARCHIVELOG mode.
• Configure the Flash Recovery Area.
Archiver(ARCn)
Archivedredo log files
Online redo log files
Archivedredo log files
Control filebackups
Data file backups
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ARCHIVELOG Mode
Archiver(ARCn)
Archivedredo log files
Online redo log files
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Configuring ARCHIVELOG Mode
To place the database in ARCHIVELOG mode, perform the following steps:• Using Enterprise Manager
– Select the “ARCHIVELOG Mode” check box. – Click Apply. The database can be set to ARCHIVELOG mode
only from the MOUNT state.– Click Yes when asked whether you want to restart the
database.• Using SQL commands
– Mount the database.– Issue the ALTER DATABASE ARCHIVELOG command.– Open the database.
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Configuring Archive Log Destinations
Online redo log files Archived
redo log filesArchived
redo log files
Online redo log files
Archivedredo log files
LOG_ARCHIVE_DEST_n
LOG_ARCHIVE_DESTLOG_ARCHIVE_DUPLEX_DEST
• Local and remote destinations:
• Local-only destinations:
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Guaranteeing Archive Log Success
Online redo log files
LOG_ARCHIVE_MIN_SUCCEED_DEST = 2
Standby1
1
2
3
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Specifying a Backup Destination
Backups can be written to:• Disk directory• Tape, using Oracle Secure Backup• Media Management Library
– Tape– Disk or tape, using proxy copy
• Flash Recovery Area: Disk area set aside for backup and recovery and flashback database purposes
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Specifying a Retention Policy
• Retention policy: Describes which backups will be kept and for how long
• Two types of retention policies:– Recovery window: Establishes a period of time within which
point-in-time recovery must be possible
– Redundancy: Establishes a fixed number of backups that must be kept
• Retention policies are mutually exclusive.
BackupSYSDATE
Recoverywindow
Backup 1SYSDATE
Backup 2
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A Recovery WindowRetention Policy: Example
Now
Recovery window of 7 days
Log 200
Backup B
Log 300
Backup C
Log 400Log 100
Backup A
Log 500
Backup B and archive logs 201 through 500 are required to satisfy this retention policy.
Backup
Backup
Obsolete
Not Obsolete
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Using a Flash Recovery Area
• Permanent items:– Multiplexed copies of the
current control file– Multiplexed copies of online redo logs
• Transient items:– Archived redo logs– Data file copies– Control file copies– Control file autobackups– Backup pieces– Flashback logs
Database
Flash Recovery Area
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Defining a Flash Recovery Area
• The Flash Recovery Area is defined by setting both of the following initialization parameters:
– DB_RECOVERY_FILE_DEST_SIZE: Sets the disk limit – DB_RECOVERY_FILE_DEST: Sets the location for the Flash
Recovery Area• These parameters are dynamic.
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Defining a Flash Recovery Area Using Enterprise Manager
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Flash Recovery Area Space Management
Space limit is reached and a new file needs to be written
into the Flash Recovery Area.
12
Backup filesto be deleted
Database filebackup
1234
Warning issued to user
Flash Recovery
Area
Space pressure occurs.
RMAN updateslist of files thatmay be deleted.
Files that are no longer
required ondisk areDeleted.
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Flash Recovery Area Space Usage
• Configure the retention policy to the minimum value appropriate for your database.
• Back up the archive log files regularly and delete the files upon completion of the backup.
• Use the RMAN REPORT OBSOLETE and DELETE OBSOLETE commands to remove backups and file copies that are not required.
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Monitoring the Flash Recovery Area
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Benefits of Using a Flash Recovery Area
Using the Flash Recovery Area for recovery-related files:• Simplifies the location of database backups• Automatically manages the disk space allocated for recovery
files
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Summary
In this lesson, you should have learned how to:• Invoke RMAN and set and list simple configurations• Configure your database in ARCHIVELOG mode• Configure multiple archive log file destinations to increase
availability• Specify a retention policy• Configure the Flash Recovery Area• Describe the benefits of using the Flash Recovery Area
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Practice 2 Overview: Configuring for Recoverability
This practice covers the following topics:• Placing the database in ARCHIVELOG mode• Verifying that the Flash Recovery Area is configured• Using RMAN to connect to the target database