One of the concise tutorials of Rman the concept and architecture of--rman

Recovery Manager (RMAN) is an Oracle tool for backup (Backup), restore (Restore), and recovery (recover) databases. Rman can only be used in ORACLE8 or higher versions. It can back up the entire database or database parts, such as tablespaces, data files, control files, archive files, and spfile parameter files. Rman also allows you to perform incremental block-level backups, and incremental Rman backups are time and space efficient because they only back up those blocks that have changed since the last backup. Moreover, with the interface provided by Rman, third party backup and recovery software such as Veritas will provide more powerful backup and recovery management capabilities. Rman also provides additional functionality, such as database cloning, the use of Rman to build standby databases, and the use of Rman to back up and move files on raw devices (raw) to become easier and simpler.

Rman is a block-level backup and recovery, backup and recovery occurs at the database block level , you can compare the data blocks to obtain a consistent block of data, you can avoid the backup of the block is not used, you can check the block to rot and other block-level problems.
For structures that comprise the above Rman, the following are described:
1. RMAN Tools
the Rman command, originating from ORACLE version 8, is typically located in the $oracle_home/bin directory and can be used to start the Rman tool by running the Rman command to back up and restore the interface.
2. Service process
The Rman service process is a background process for communication with the Rman tool and the database, and also for the communication between the Rman tools and the I/O settings such as disk/tape, and the service process is responsible for all the work of backup and recovery and will produce a service process as follows

• When connecting to the target database
• Assigning a new channel
3, channel
        Channel is a service process and I/O The way to read and write before the device, a channel will correspond to a service process, in the allocation of channels, you need to consider the type of I/O device, I/O concurrency processing capacity, I/O device can create file size, database file maximum read rate, maximum number of open files, etc. The target database
        is the database in which Rman backs up and restores, and Rman can back up data files other than online logs, pfile, and password files , control files, archive logs, SPFile.

5, restore the directory
a database used to hold backup and recovery information, not recommended for creation on the target database, using the recovery directory to
To manage multiple target databases at the same time, store more backup information, and store backup scripts. If you do not use the recovery target
Records, you can use the control file to replace the recovery directory, Oracle 9i because the control of automatic file backup function, the use of control
The file can largely replace the recovery directory.
6, the media management layer
Media Management Layer (MML) is a third-party tool or software that manages the reading and writing of tapes and files
Track management. If you want to back up to tape directly through Rman, you must configure the media management layer, media management
Tools such as backup software can invoke Rman for backup and recovery.
7. Backup, backup set and backup slice
when the backup command is issued, RMAN creates a completed backup containing one to more than one backup set, which is a logical structure containing a set of physical files. These physical files are the corresponding backup slices. A backup slice is the most basic physical structure that can be generated on a disk or tape and can contain data files, control files, archive logs, and SPFile files for the target database.
Backup sets and backup slices have the following provisions: A data file can not span a backup set, but can span the backup slice;

Data files, control files can be saved on the same backup set, but cannot be saved with the archive log on the same backup set.
Recommended Oracle Community: HTTP://WWW.PDMCN.COM/BBS, Oracle QQ Group: 60632593, 60618621

          Recommended Oracle Technical materials: Oracle 9i Rman Reference Manual, oracle10g backup and recovery, Oracle Database 10gRMAN Backup and recovery