Oracle8 Backup and Recovery Guide Release 8.0 A58396-01 |
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# 5
Choosing a Backup Method

This chapter describes the different backup methods available and situations when each should be used, and contains the following topics:

- Backup Methods and Requirements
- Recovery Manager
- Feature Comparison of Backup Methods

## Backup Methods and Requirements

This section describes the various Oracle backup methodologies and requirements associated with each, and includes the following topics:

- Table 5-1 identifies additional requirements associated with the different backup methods.
- Operating System (O/S)
- Enterprise Backup Utility (EBU)
- Export

Table 5-1 identifies additional requirements associated with the different backup methods.

##### Table 5-1 Requirements for Different Backup Methods

Backup Method | Version Available | Requirements
--- | --- | ---
Recovery Manager | Oracle8 | Media Manager (if backing up to tape)
O/S | All versions of Oracle | O/S backup utility (for example, UNIX dd)
Export | All versions of Oracle | N/A
Enterprise Backup Utility (EBU) | Oracle7 | Media Manager (if backing up to tape)

### Recovery Manager

The Recovery Manager utility manages the backup, restore and recovery operations of Oracle databases. Recovery Manager uses information about the database to automatically locate, then back up, restore and recover datafiles, control files and archived redo logs.

### Operating System (O/S)

An O/S backup is performed via a native command on your O/S, which is used to make backups of Oracle database files. For example, you can use the `dd' or `tar' commands to create UNIX O/S backups. O/S backups are controlled by UNIX scripts written and maintained by the Database Administrator, and/or the System Administrator.

See Also: For information about the utilities available on your operating system, see your operating system-specific documentation.

### Export

The Oracle Export utility writes data from an Oracle database to operating system files in an Oracle database format. Export files store information about schema objects created for a database. Because the Oracle Export utility can selectively export specific objects, you may consider exporting portions of or all of a database for supplemental protection and flexibility. Database exports are not a substitute for whole database backups and don't provide the same recovery advantages that the built-in functionality of Oracle offers.

See Also: For information about using exports to supplement your backup strategy, see Oracle8 Utilities.

### Enterprise Backup Utility

The Oracle Enterprise Backup Utility is available to back up Oracle7 databases; it is not compatible with Oracle8 databases.

See Also: For information about using the EBU to back up an Oracle7 database, see the Oracle7 Enterprise Backup Utility Administrator's Guide.

## Recovery Manager

The Recovery Manager utility manages the backup, restore and recovery operations of Oracle databases. Recovery Manager uses information about the database to automatically locate, then back up, restore and recover datafiles, control files and archived redo logs.

Recovery Manager gets the required information from either the databases' control file, or via a central repository of information called a recovery catalog, which is maintained by Recovery Manager.

### Using Oracle Enterprise Manager to Perform Recovery Manager Backups

You can perform Recovery Manager backups using Oracle Enterprise Manager. Oracle Enterprise Manager-Backup Manager is a GUI interface to Recovery Manager that enables you to perform backup and recovery via a point-and-click method.

See Also: For information about performing backup and recovery using Oracle Enterprise Manager, see the Oracle Enterprise Manager Administrator's Guide.

### Recovery Manager is Different from Traditional Operating System Backups

Recovery Manager is a command line interface (CLI) that directs an Oracle server process to back up, restore or recover the database it is connected to.

The Recovery Manager program issues commands to an Oracle server process.The Oracle server process reads the datafile, control file or archived redo log being backed up, or writes the datafile, control file or archived redo log being restored or recovered.

When an Oracle server process reads datafiles, it detects any split blocks and re-reads them to get a consistent block. Hence, you should not put tablespaces in hot backup mode when using Recovery Manager to perform open backups.

See Also: "Fractured Block Detection During Open Database Backups in Recovery Manager".

Recovery Manager performs backup and recovery procedures, and greatly simplifies the tasks administrators perform during these processes. For example, Recovery Manager provides a way to:

- Configure frequently executed backup operations
- Generate a printable log of all backup and recovery actions
- Use the recovery catalog to automate both media restore and recovery operations
- Perform automatic parallelization of backups and restores
- Find datafiles that require a backup based on user-specified limits on the amount of redo that must be applied
- Back up the database, individual tablespaces or datafiles

### Backups to Disk

You can use Recovery Manager to perform backups to disk. You don't need to integrate Oracle with any Media Managers if you only intend to write backups to disk.

### Backups to Sequential Media

Attention: In order to utilize tape storage for your Oracle database backups, Recovery Manager requires you to install a media management product. The Oracle Backup Solutions Program (BSP) provides customers with a range of media management products that are compliant with the Oracle Media Management interface specification. One of these products is the Legato Storage Manager (LSM), which is available for a number of platforms, and is included in the Oracle software shipped for those platforms. Refer to your platform-specific documentation for information regarding availability of the Legato product on your platform. The Legato Storage Manager Administrator's Guide describes the features supported by this product. If other BSP media management products are included with your shipment, they will be documented in your platform-specific documentation. Several other products may be available for your platform directly from a media management vendor. For a current list of available products, refer to the Oracle Backup Solutions Program (BSP) web site at: http://www.oracle.com/st/products/features/backup.html You can also contact your Oracle representative for a complete list. If you wish to use a particular media management product, contact the media management vendor directly to determine if they are a member of the Oracle Backup Solutions Program.

To make backups to sequential media (such as tape) using Recovery Manager, you must have media management software integrated with the Oracle software.

Figure 5-1 shows the architecture for media management software integrated with Oracle.

#### Figure 5-1 Architecture for MML Integrated with Oracle

The Oracle executable is the same one started when a user connects to the database. The MML (Media Management Library) in the diagram above represents Media Management vendor-supplied software that can interface with Oracle. Oracle calls MML software routines to back up and restore datafiles to and from media controlled by the Media Manager.

The following Recovery Manager script performs a datafile backup to a tape drive controlled by a Media Manager:

    run {
       allocate channel t1 type `SBT_TAPE';
       backup
          format `df_%s_%t'
          (datafile 10);
    }

When Recovery Manager executes the above command, it sends the backup request to the Oracle server performing the backup. The Oracle server process identifies the output channel as the type `SBT_TAPE', and requests the Media Management Library to load a tape and write the output specified.

When Oracle requests the restore of a particular file, the Media Manager identifies the tape the file is on, reads the tape, and passes the information back to the Oracle server process, which then writes the file to disk.

The Media Manager labels and keeps track of the tape and names of files on each tape. If your site owns an Automated Tape library with robotic arm, the Media Manager will automatically load and unload the tapes required by Oracle; if not, the Media Manager will request an operator to load a specified tape into the drive.

The Oracle server doesn't need to connect to the MML software when a backup is written to disk. The Oracle executable writes backups to disk without third party integration software.

## Feature Comparison of Backup Methods

Table 5-2 compares the features of the backup methods described in this chapter

##### Table 5-2 Feature Comparison of Backup Methods

Feature | Recovery Manager | Operating System | Export
--- | --- | --- | ---
closed database backups | Supported. Requires instance to be mounted. | Supported. | Not supported.
open database backups | You do not use BEGIN/END BACKUP commands. | Generates more redo when using BEGIN/END BACKUP commands. | Requires RBS to generate consistent backups.
incremental backups | Supported. Backs up all modified blocks. | Not supported. | Supported, but not a true incremental, as it backs up a whole table even if only one block is modified.
corrupt block detection | Supported. Identifies corrupt blocks and writes to V$BACKUP_CORRUPTION or V$COPY_CORRUPTION. | Not supported. | Supported. Identifies corrupt blocks in the export log.
automatically backs up data | Supported. Establishes the name and locations of all files to be backed up (whole database, tablespace, datafile or control file backup). | Not supported. Files to be backed up must be specified manually. | Supported. Performs either full, user or table backups.
catalogs backups performed | Supported. Backups are cataloged to the recovery catalog and to the control file, or just to the control file. | Not supported. | Not supported.
makes backups to tape | Supported. Interfaces with a Media Manager. | Supported. Backup to tape is manual or managed by a Media Manager. | Supported.
Backs up init.ora and password files | Not supported. | Supported. | Not supported.
Operating System Independent language | An O/S independent scripting language. | O/S dependent. | O/S independent scripting language.

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