Shulou(Shulou.com)06/01 Report--

Backup:

Definition:

The process of copying a database to a dump device.

Dump device:

The tape or disk on which the copy of the database is placed.

Backup of the original database:

A copy of the database stored in the dump device.

Classification:

Physical and logical perspective:

Physical backup:

Backup of physical files (data files, control files, log files) of the database.

Divided into:

Offline backup (cold backup):

The database must be closed.

Online backup (hot backup):

Back up the running database as an archive log.

Recovery Manager (RMAN) for available oracle

Or operating system command to make a physical backup.

Logical backup:

Backup of database logical components (tables, stored procedures, etc.).

EXP, data pump (EXPDP), database flashback technology and other third-party tools backup.

Database backup point of view:

Full backup:

Complete backup of the database to achieve 100% data recovery.

The recovery time is shortest and the operation is the most convenient.

Incremental backup:

Files that were modified after the last full or incremental backup are backed up.

Advantages:

The amount of backup data is small and the time is short.

Disadvantages:

Restore relies on previous backup records. The risk is greater.

Differential backup:

Back up files that have been modified since the last full backup. The recovery time is short.

Two pieces of data are required:

Last full backup.

The last differential backup.

Disadvantages:

Each backup takes a long time.

Restore:

Definition:

After a failure, use the backed-up data files or control files to re-establish the complete database.

Classification:

Instance recovery:

The instance fails and oracle recovers on its own.

Media recovery:

Restore in the event of a failure of the storage database media.

Divided into:

Full recovery:

Revert to the state before the data failed.

This is done by loading the database backup and applying all the redo logs.

Incomplete recovery:

Restore to the state at some point before the database failed.

This is done by loading the database backup and applying part of the redo log.

Reset the online redo log with the resetlogs option when starting the database.

Use the RMAN tool:

Storage type:

Backup set

Compress backup set

Mirror copy

Backup film:

Each file that makes up each backup set

RMAN backup storage location (2):

The control file of the target database

Restore in the directory.

Advantages of RMAN backup:

RMAN backs up only valid data

RMAN enables incremental backups.

Function:

Backup and restore data files, archive logs, control files.

Perform a full or incomplete database recovery.

Three different user interfaces:

Command line mode

GUI mode (backup Manager)

API mode (integrated into backup software)

Features:

Online hot backup is supported.

Multi-level incremental backups are supported.

Support for parallel backup and recovery.

Reduce the amount of spare parts needed.

Backup, recovery is easy to use.

RMAN components:

Target database (target database):

RMAN is required to back up and restore it.

Service session (server session)

RMAN starts the oracle server process on the database

A conversation with the target database will be established.

RMAN Repository (RMAN database):

Control information that will be used during the use of RMAN.

Recovery Catalog (recovery catalog):

A schema object established on the RMAN recovery catalog database

Used to save RMAN database data.

It is recommended that you set up a recovery directory in a separate database and save another copy of the database data.

MML (Media Management Library):

Manage the reading and writing of tapes and the tracking management of files.

Media management tools work with RMAN to complete backups and restores.

Flash recovery area:

Save the default disk location for all recovery-related files. Including archive logs, RMAN backups

Automatic backup of control files, reused control files and redo log copies and flashback log files.

Secondary database:

Use RMAN to create a new database from a backup of the target database.

Can be used as a backup database.

Create a recovery directory:

Exists in the catalog database of RMAN.

Contains the following sections of information:

Backup and restore information.

RMAN script, which can be stored for reuse.

Backup information for data files and log files.

The tablespace and data file information of the target database.

The RMAN database can be stored in the target database control file or in the recovery directory.

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