Thursday, June 28, 2012

How to Backup & Recover Oracle Database

Backup and recovery are two pillars of Oracle database which helps to protect your database against data loss and reconstruct the database. Backup is a copy of data from your database that can be used to reconstruct that data if any data loss condition occurs. Generally for any database, Backups can be divided into two parts: physical backups and logical backups.
Physical backups are called backups of the physical files such as datafiles, control files, and archived redo logs which is used to restore & recover database,. Ultimately, the physical backup means copy of files storing database information to some other location either on disk or some offline storage such as tape.
Logical backups contain logical data like tables or stored procedures export (Oracle export utility) from a database and stored in a binary file, for later re-importing into a database using the corresponding Oracle import utility.
In this article, I am describing the methods to perform backup and recovery based on physical backups, you have two solutions available:
First one is RMAN that can back up all database files such as Datafiles, Control files, Archived redo logs etc which is needed for efficient recovery in the event of data loss. You can easily easily find in ORACLE_HOME/bin directory. We can operate RMAN from Oracle Enterprise Manager, or from command line.
Second one is traditional user-managed backup and recovery used to directly manage the files through OS commands to perform backup and restore operations, and after that use SQL or SQL*Plus statements to recover database.
You can choose any one backup and recovery solution according to your requirements. Check the features that you want to backup & recover your database:
Closed database backups
Supported.Requires instance to be mounted.

Open database backups
Supported. No need to use BEGIN/ END Backup statements
Supported. Must use BEGIN/ END Backup statements
Incremental backups

Not supported.
Corrupt block detection
Supported. Identifies corrupt blocks and logs in V$DATABASE_BLOCK_CORRUPTION.

Not supported.
Automatic record
Supported. Establishes the name and locations of files to be backed up (whole database, tablespace, datafile or control file backup).
Not supported. Files to be backed up must be specified manually.
Recovery catalogs
Supported. Backups are recorded in the RMAN repository, which is contained in the control file and optionally in the recovery catalog database.
Not supported. DBA must keep own records of backups.
Backups to media manager
Supported. Interfaces with a media manager. RMAN is also supports proxy copy, a media manager. a feature that allows the media manager to manage the transfer of data.
Supported. Backup to tape is manual or controlled by a media manager

Backs up initialization parameter file

Backs up password and networking files

Not Supported.
Platform-independent language for backups

Not Supported.

Most of the users thinks that RMAN is very complicated but in actual it is very easy,even also Oracle recommended using RMAN to take oracle database backup & recovery Because there are many options for oracle database backup which are not available in User Managed. So As per my view, RMAN is one the best way to recover oracle database.

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