RMAN Architecture Overview

I. rediscovery Manager (RMAN) Features

RMANIt is an oracle tool that integrates backup, recovery, and recovery databases. It supports command line and graphic interface operations.

A. It can back up the entire database, tablespace, data files, control files, archive files, and spfile parameter files.

B. Support for incremental data block-level backup and block-level media recovery

C. You can save frequently executed Backup Recovery scripts.

D. you can clone databases and use RMAN to create backup databases.

E. Supports image backup and backup set, which can be backed up to disks and tapes.

F. Increase backup concurrency or limit I/O to reduce the impact of backup on the database

G. Check damaged data blocks during Backup

Ii. RMAN Components

1. RMAN executableProgram: Rman.exe in Windows OS and RMAN in UNIX OS

2. target database

A. The target database refers to the database to be backed up, restored, and restored. RMAN executable programs can only connect to one database at a time

B. the control file of the target database stores the information required by RMAN (when the control file is used by the storage warehouse). RMAN reads the control file to determine the physical structure of the target database, the location and archive information of the data file to be backed up. When RMAN is used, the control file is updated.

3. Server Processes and channels

RMAN can connect to an instance remotely or locally through a common Server session and call PL/SQL. After RMAN is started, a common server process is generated. Once the backup and restoration operations are started, RMAN enables one or more channels based on the configuration. In short, the channel is the server process that completes file replication, and multi-channel operations are performed in parallel.

4. storage warehouse

The storage warehouse stores metadata related to the target database and its backup;

Contains detailed information about the physical structure of the target database and the location of data files;

Details of all completed backups;

The permanent configuration information of RMAN;

The storage warehouse is always stored in the control file of the target database or in the recovery directory (a separate Oracle database );

The control_file_record_keep_time parameter determines the minimum number of days for Repeatable records in the control file.

When a new record needs to be added to the reusable record space, and the oldest record is not aging in the reusable record space, that is, if the number of days actually retained does not exceed the number of days specified by this parameter, the space of the reusable record section in the control file will be automatically expanded, and the size of the control file will increase.

5. Restore the Directory

The backup and recovery of the target database, metadata, and other related information can be written to a separate database, which is the recovery directory;

The recovery directory can store RMAN scripts, instead of operating system files;

The contents of the recovery directory usually include: data files, archived log backup sets, backup slices, image copies, RMAN storage scripts, and other permanent configuration information;

We recommend that you place the recovery directory on a host different from the target database;

6. auxiliary database (standby database $ duplicate database)

Standby Database: a copy of the target database. It is updated using the archived log of the target database (primary database) and does not have a unique dbid;

RMAN can create or back up standby databases, which can be used for primary database failover;

Duplicate Database: it is a copy or subset of the target database and has a unique dbid, which is independent of the primary database and can be registered as a primary database in the same recovery directory;

Tspitr (tablespace point-in-time recovery): Restores one or more tablespaces to a non-current state while retaining the current State for other tablespaces;

7. Backup destination

The default backup destination is the flash back area, $ oracle_base/flash_recovery_area /;

You can set the db_recovery_file_dest parameter and db_recovery_file_size to adjust it;

Iii. Parameters Affecting RMAN

Database initialization parameters:

Control_file_record_keep_time -- specifies the minimum number of days before the RMAN information in the control file is overwritten.

Db_recovery_file_dest -- If RMAN is backed up here, you need to set this parameter

Db_recovery_file_dest_size -- If you back up RMAN here, you need to set this parameter

Environment variable parameters:

Nls_date_format -- set the date

Nls_lang -- set environment variables to affect restore, recover, report, and other commands

Iv. Backup-related dynamic performance view and monitoring

1. Related views

 1   V $ backup_files  2 V $ backup_set --  Show created backup Sets  3 V $ backup_piece --  Displays the backup slices created for the backup set.  4 V $ backup_redolog --  Displays the archived logs stored in the backup set. 5   V $ backup_spfile  6   V $ backup_device  7 V $ rman_configuration --  RMAN configuration information  8 V $ archived_log --  Displays the archive files that have been created, backed up, or cleared in the database.  9 V $ backup_upload uption --  Shows the damaged blocks found during backup of the Backup set.  10 V $ copy_uption --  Displays damaged blocks found during image copying.  11   V $ database_block_corruption  12 V $ backup_datafile --  Used to create a backup set of the same size by determining the number of blocks in each data file. You can also find the number of corrupted blocks in the data file. 

2. view the Server sessions corresponding to the Channel

 1 SQL >   Select Sid, username, client_info From  V $ session 2     2    Where Client_info Is   Not   Null  ;  3   4   Sid username client_info  5   --  --------------------------------------------------------------------  6          146 Sys RMAN Channel =  Ora_disk_1  7          148 Sys RMAN Channel =  Ora_disk_2  8          150 Sys RMAN Channel = Ora_disk_3

3. view the complete RMAN progress

 1 SQL >   Select Sid, serial #, context, SOFAR, totalwork,  2     2    Round (SOFAR / Totalwork *  100 , 2 )" %  Complete"  3     3    From  V $ session_longops 4     4     Where Opname Like   '  RMAN: %  '  5     5    And Opname Not   Like   '  RMAN: Aggregate %  '  6    6    And Totalwork ! =  0 ;