Recovery manager (RMAN) is a command line utility used to perform backup and recovery operations. RMAN provide greater ease of management and administration of the backup and recovery operations.

Benefits of recovery manager

The key objective of RMAN (recovery manager) is to provide greater ease of management and administration of the backup and recovery operations. RMAN and the oracle server minimize operational errors, by automating the backup and recovery process, and by performing multiple consistency checks throughout the procedure.

RMAN decides how to execute backup, restore, or recovery operations based on information in the database's recovery catalog, control file, and the current state of the datafiles, then instructs and coordinates oracle server processes to perform the desired operation.

CONFIGURE rman command is the configuration mechanism for RMAN envrionment. These settings (rman configuration) apply to all RMAN sessions until explicitly changed or disabled. SHOW command is use to display the rman configurations for one or more databases.

The CONFIGURE rman command always stores a rman configuration for a target database in the target database control file. If you use a recovery catalog, then RMAN also stores rman configuration settings for each registered database in the catalog.

Connecting to RMAN can be achieved by simply typing rman at the operating system prompt. some of the common operation are as follows

• Syntax of RMAN connect Command
• Connecting to RMAN without any Connection
• Connecting to RMAN With Target Database
• Connecting to RMAN With Recovery Catalog
• Connecting to RMAN Without Recovery Catalog
• Exiting RMAN

RMAN CONNECT command establishs a connection between RMAN and a target, auxiliary, or recovery catalog database.

• RMAN CONNECT command connections to a target or auxiliary database require the SYSDBA privilege. The AS SYSDBA keywords is not required while connecting
• Use CONNECT command at the RMAN prompt and only if RMAN is not already connected to the database.
• To connect to a different target, catalog, or auxiliary database start a new RMAN session.

Following is the RMAN command list mostly used during the rman backup and recovery operations. These rman commands can be executed at RMAN prompt, or within a RUN block.

The most important rman command is RMAN BACKUP command that is used to backup database files. While RMAN RECOVER command used to recover from database failues and apply redo log files from backup to update them. Before using RECOVER command you must use RESTORE command to restor database files from backup.

The rman DUPLICATE command is another RMAN command used to create duplicate or copy database to another machine using previous backups for checking backups or testing purpose.

The SQL*Plus auto trace is another method to get actual execution plan with some additional statistics. When set to ON automatically display execution plan after each SQL statement with Statistics

1. Query that will return the trace file for a given session or for all sessions attached to the database. You should be connected as SYSDBA
2. Automation for Enabling and disabling SQL Trace

SQL Trace and TKPROF let you to accurately assess the efficiency of the SQL statements when an application runs. For best results, use these tools with EXPLAIN PLAN rather than using EXPLAIN PLAN alone.

An execution plan is the sequence of operations Oracle performs to run the statement. The EXPLAIN PLAN statement displays execution plans chosen by the Oracle optimizer for SELECT, UPDATE, INSERT, and DELETE statements.

When a SQL query is submitted to an Oracle database, Oracle query optimizer decide how to access the data. The process of making this decision is called query optimization, Oracle looks for the optimal way to retrieve the data, using the execution path.

RMAN DUPLICATE command creates duplicate database or clone from backups of the target database while retaining the original target database. The cloned database is a identical copy or original database.

The duplicate database can be identical to the target database or contain only a subset of the table-spaces in the target database. The target site and the duplicate site can be on separate hosts or on the same host.

The Duplicate DB can run independently and used for several reasons for example:

• Test backup and recovery procedures
• Export data such as a table that was inadvertently dropped from the production database, and then import it back into the production database
• cloned database can be used to transfer from production server to testing server or moving cloned database from one location to another.

There are several ways to check for corruption in an Oracle database

1. Using DBVERIFY command
2. Using ANALYZE command

1. How to Schedule backups using enterprise manager?
2. How to relocate archive-log backups to different disk location?
3. How to recover whole database without backup if all Control Files are lost?
4. How to restore and recover from loss of datafiles and tablespaces?

Oracle Flashback Technology provides a set of new features to view and rewind data back and forth in time. The Flashback features offer the capability to query historical data, perform change analysis, and perform self-service repair to recover from logical corruptions while the database is online. With Oracle Flashback Technology, you can indeed undo the past!

RMAN maintain metadata in repository about target database, its backup and recovery operations. For example (own configuration setting, target database schema, archived redo logs and backup files on disk or tap).