Introduction to RMAN Oracle
Oracle RMAN stands for Oracle Recovery Manager. It is an Oracle Database Client that automates backup and recovery tasks on your databases. It performs backing up, recovering and restoring the database files. Data backup administrators are not required to start the backup process. DBA (Database Administrators) can protect data on Oracle databases by using RMAN (Recovery Manager).
What is RMAN Oracle?
RMAN (Recovery Manager) is an Oracle database client, which automates the administration of backup strategies and guards the database integrity. During restoring and backing up of data, Block level corruption detection is given. Many backup techniques like backup files retention policy, parallelization of backup or restore data streams and backup operation’s detailed history are all supported. Oracle Recovery Manager can conduct block media recovery, automated database duplication, incremental backups, cross-platform data conversion, binary compression, and encrypted backups. It handles all these maintenance tasks that are performed before or after the backup or recovery of the databases.
RMAN Oracle Architecture
Oracle Recovery Manager (RMAN) architecture has the following components:
- Target database: It is a database, which contains data files, controls files and redo files that are needed to be backed up or recovered. The target database control file is used by RMAN to collect metadata about the target database. Server sessions running on the target database perform all the backup and recovery work. It is a mandatory component for RMAN.
- RMAN client: It is the client application that performs all the backup and recovery operations for the target database. It uses Oracle net to connect to the target database so that its location can be found on any host that is connected to the target host using Oracle Net. It is a command line interface which helps in issuing the backup, recover, SQL and special RMAN commands. It is a mandatory component for RMAN.
- Recovery catalog schema: It is the user present in the recovery catalog database that has the metadata tables made by RMAN. RMAN periodically shifts metadata from the control file of the target database to the recovery catalog. It is an optional component.
- Recovery catalog database: It is a database that contains the recovery catalog that contains metadata which is used by RMAN to perform backup and recovery tasks. One recovery catalog can be created for containing metadata of multiple target databases. It is also an optional component.
- Physical standby database: It is a copy of the primary database which is updated with archived redo logs. It has the same Database id and database name as the primary database, but it has different DB_UNIQUE_NAME. Standby databases can be created, backed up and recovered by RMAN. It is not a mandatory component.
- Duplicate database: It is also a copy of the primary database but it is used for testing purposes. Its DB_ID is also different from the primary database.
- Fast recovery area: It is a disk location used to store files related to recovery such as control file, online redo files flashback logs, RMAN backups, and archived redo files. Files present in the fast recovery area are automatically managed by the Oracle database and RMAN.
- Media Manager: It is a vendor-specific application that allows RMAN to back up the storage system such as tape. It is an optional component.
- Media Management catalog: It is a vendor-specific repository of metadata related to media management application. It is also an optional component.
- Oracle Enterprise Manager: It is a browser-based interface which includes backup and recovery through RMAN. It is also an optional component.
How RMAN works
The RMAN environment has a target database and an RMAN client. Backups are performed on target databases by RMAN and the client application manages all the backup and recovery tasks for the target database. A media manager API is used by RMAN to work with the backup hardware. A user must log in to Oracle RMAN and then ask it to back up the user’s database. RMAN then copies the file to the user-specified directory.
Database Administrators can use RMAN backup commands to manage RMAN. Commands can be used to convert data files, to run a backup, to update or recover catalog schemas, initiate a flashback database, create a duplicate database and many more tasks.
Features of RMAN
- Backup sets: The backup sets are made up of backup pieces in which Oracle RMAN stores data. A backup piece is a binary file which can only be created or restored by RMAN. Backup sets are formed by grouping backup pieces which enables database administrators to protect multiple data files, archive logs, and server parameter files. Data written in backup sets can be encrypted and decrypted by RMAN.
- Archived redo logs: Every database of Oracle has its redo log which store changes made to the database. Archived redo logs contain the group of redo logs saved off-site. If the database does not shut down properly then it leads to an inconsistent database which can be restored using archived redo logs.
- Flash Recovery: The backups done made by RMAN are created in the flash recovery area of the Oracle database on the disk. FRA is a directory that has online and archived redo logs, control logs, flashback logs, and image copies. The backups which are not required anymore are removed to make free space for new backups. The backups to be deleted are decided according to the policies made by DBA.
- Flashback Database and Media Recovery: Oracle Flashbacks and Media recovery are used to restore data. Flashbacks allow DBAs to go to a previous time to remove user errors or data corruptions called point-in-time recovery. The media failures are resolved using Media Recovery. Flashback database helps to restore any database entirely at any point in time instead of doing incomplete recovery.
- Encrypting backup sets: There are three encryption modes provided by RMAN i.e. Transparent Encryption, Dual Mode Encryption, and Password Encryption.
Advantages of RMAN
- Selects the most appropriate backup for database recovery.
- Uses simple commands.
- User can automatically backup the database on tape.
- A database can be recovered in the data block level.
- Only changed data blocks can be recovered using incremental backup functionality which reduces the backup time.
- Secure backups can be created using the Encryption feature.
- Clone of the database can be created on the remote host by using the duplicate command of RMAN.
- Physical standby databases can be created simply.
How this technology will help you in career growth?
Due to an increase in data, the process of handling database and the fear of losing data is also increasing. So database recovery is required and hence the job opportunities for this are also increasing. The average salary of the jobs related to Oracle RMAN ranges from $87,000 to $131,000 per year.
This article is related to the basic concepts and working of Oracle RMAN whose scope is increasing day by day due to increase in data, hence it is an efficient database client which helps in recovering the databases easily.
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