使用Oracle自带的备份恢复工具RMAN(Recovery Manager)具有以下几种优势：
支持增量备份
能自动管理备份文件
自动化备份与恢复
备份的文件有效性检查
配置快闪恢复区（flash recovery area）
快闪恢复区是存储备份和恢复数据文件以及相关信息的存储区。需要设置两个参数：db_recovery_file_dest_size(快闪恢复区的最大容量)，db_recovery_file_dest(快闪恢复区所在的路径)。
查看快闪恢复区信息：
SQL> show parameter db_recovery_file_dest; NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ db_recovery_file_dest string /data/app/oracle/recovery_area db_recovery_file_dest_size big integer 3882M
修改快闪恢复区大小：
SQL> alter system set db_recovery_file_dest_size=2g; System altered. SQL> show parameter db_recovery_file_dest; NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ db_recovery_file_dest string /data/app/oracle/recovery_area db_recovery_file_dest_size big integer 2G
查看使用情况：
SQL> select name,space_limit,space_used,number_of_files from v$recovery_file_dest; NAME -------------------------------------------------------------------------------- SPACE_LIMIT SPACE_USED NUMBER_OF_FILES ----------- ---------- --------------- /data/app/oracle/recovery_area 2147483648 0 0
显示没有使用。
也可以使用此命令查看详细信息：
SQL> select file_type,percent_space_used,percent_space_reclaimable,number_of_files from v$flash_recovery_area_usage;
建立RMAN到数据库的连接
创建rman用户，并授权：
[oracle@temp-test oracle]$ sqlplus /nolog SQL> connect/as sysdba Connected. SQL> create user rman identified by oracle; User created. SQL> grant resource,connect,dba to rman; Grant succeeded. SQL> quit
使用rman用户登录RMAN:
[oracle@temp-test oracle]$ rman target rman/oracle Recovery Manager: Release 11.2.0.1.0 - Production on Fri Nov 3 16:59:27 2017 Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved. connected to target database: ORCL (DBID=1486802665) RMAN>
也可以使用如下方式登录：
[oracle@temp-test oracle]$ rman Recovery Manager: Release 11.2.0.1.0 - Production on Fri Nov 3 17:00:35 2017 Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved. RMAN> connect target system/rman connected to target database: ORCL (DBID=1486802665) RMAN> connect target rman/oracle
也可以使用操作系统认证连接RMAN：
[oracle@temp-test oracle]$ rman target / Recovery Manager: Release 11.2.0.1.0 - Production on Fri Nov 3 17:02:52 2017 Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved. connected to target database: ORCL (DBID=1486802665) RMAN>
配置RMAN
查看RMAN的配置参数：
RMAN> show all; using target database control file instead of recovery catalog RMAN configuration parameters for database with db_unique_name ORCL are: CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default CONFIGURE BACKUP OPTIMIZATION OFF; # default CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default CONFIGURE MAXSETSIZE TO UNLIMITED; # default CONFIGURE ENCRYPTION FOR DATABASE OFF; # default CONFIGURE ENCRYPTION ALGORITHM 'AES128'; # default CONFIGURE COMPRESSION ALGORITHM 'BASIC' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE ; # default CONFIGURE ARCHIVELOG DELETION POLICY TO NONE; # default CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/data/app/oracle/product/11.2.0/dbhome_1/dbs/snapcf_orcl.f'; # default
参数含义：
CONFIGURE RETENTION POLICY TO REDUNDANCY 1
保留的备份副本数量，表示只保留一个数据文件的副本，并且保留最新的备份副本。
CONFIGURE DEFAULT DEVICE TYPE TO DISK
数据文件默认备份到磁盘上，也可以是其他设备如磁带（sbt）
CONFIGURE BACKUP OPTIMIZATION OFF
不使用备份优化，启用备份优化的作用是如果已经备份了某个文件的相同版本，则不会再备份该文件。，只保留一份备份文件。
CONFIGURE CONTROLFILE AUTOBACKUP OFF
不启动控制文件的自动备份，修改为ON之后，如果数据库结构发生变化或者在备份数据库过程中，控制文件会自动再备份到指定目录下
CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET
备份通道数量为1，默认使用备份集的方式。通道数量越多，执行任务时间越短。
如果要修改参数，可以执行如下命令：
开启备份优化：
RMAN> CONFIGURE BACKUP OPTIMIZATION ON; new RMAN configuration parameters: CONFIGURE BACKUP OPTIMIZATION ON; new RMAN configuration parameters are successfully stored
设置备份类型为Copy，也就是映像模式:
RMAN> CONFIGURE DEVICE TYPE DISK BACKUP TYPE TO COPY; new RMAN configuration parameters: CONFIGURE DEVICE TYPE DISK BACKUP TYPE TO COPY PARALLELISM 1; new RMAN configuration parameters are successfully stored
备份控制文件到快闪恢复区：
RMAN> backup current controlfile; Starting backup at 03-NOV-17 using channel ORA_DISK_1 channel ORA_DISK_1: starting datafile copy copying current control file output file name=/data/app/oracle/recovery_area/ORCL/controlfile/o1_mf_TAG20171103T180113_dzrhm9vk_.ctl tag=TAG20171103T180113 RECID=3 STAMP=959104874 channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:01 Finished backup at 03-NOV-17
如果没有指定快闪恢复区也可以用手动指定路径：
将快闪恢复区改为test目录
SQL> connect/as sysdba Connected. SQL> show parameter db_recovery_file_dest; NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ db_recovery_file_dest string /data/app/oracle/recovery_area db_recovery_file_dest_size big integer 2G SQL> alter system set db_recovery_file_dest='/data/app/oracle/test'; System altered. SQL> show parameter db_recovery_file_dest; NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ db_recovery_file_dest string /data/app/oracle/test db_recovery_file_dest_size big integer 2G
配置控制文件备份的磁盘类型和备份目录，路径以%F结尾：
RMAN> configure controlfile autobackup format for device type disk to '/data/app/oracle/test/%F'; new RMAN configuration parameters: CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '/data/app/oracle/test/%F'; new RMAN configuration parameters are successfully stored
RMAN脱机备份
RMAN脱机备份需要关闭数据库，启动数据库到mount状态。
[oracle@temp-test oracle]$ sqlplus /nolog SQL> connect/as sysdba Connected. SQL> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. SQL> startup mount; ORACLE instance started. Total System Global Area 1586708480 bytes Fixed Size 2213736 bytes Variable Size 939526296 bytes Database Buffers 637534208 bytes Redo Buffers 7434240 bytes Database mounted. SQL> quit
进入RMAN，备份数据：
先查看数据备份的默认参数，备份方式（copy或backupset），和备份格式(disk 或其他)
RMAN> show all; using target database control file instead of recovery catalog RMAN configuration parameters for database with db_unique_name ORCL are: CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default CONFIGURE BACKUP OPTIMIZATION ON; CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default CONFIGURE DEVICE TYPE DISK BACKUP TYPE TO COPY PARALLELISM 1; CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default CONFIGURE MAXSETSIZE TO UNLIMITED; # default CONFIGURE ENCRYPTION FOR DATABASE OFF; # default CONFIGURE ENCRYPTION ALGORITHM 'AES128'; # default CONFIGURE COMPRESSION ALGORITHM 'BASIC' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE ; # default CONFIGURE ARCHIVELOG DELETION POLICY TO NONE; # default CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/data/app/oracle/product/11.2.0/dbhome_1/dbs/snapcf_orcl.f'; # default
执行备份命令使用copy方式，映像复制整个库：
RMAN> backup as copy database;
如果是使用默认的backupset模式，可以使用：
RMAN> backup as compressed backupset database;
备份完成后，打开数据库：
RMAN> sql 'alter database open'; sql statement: alter database open
RMAN联机备份整个数据库
联机备份必须要设置快闪恢复区，快闪恢复区要足够大，并且数据库要置于归档模式。在数据库进行备份的同时，可以进行DML操作，可以正常读取，新的DML操作记录会在重做日志文件中,如果备份时间很长，而且在这个期间产生了大量的数据变化，重做日志会切换从而将这些变化的数据写到归档日志文件中。这里的归档日志就类似于mysql的binlog,在出现介质故障的时候，使用备份和归档日志记录和完成数据的全部恢复。
查看数据库归档模式是否开启，当前属于关闭状态：
SQL> archive log list; Database log mode No Archive Mode Automatic archival Disabled Archive destination USE_DB_RECOVERY_FILE_DEST Oldest online log sequence 22 Current log sequence 24
开启日志归档：
SQL> alter database archivelog; alter database archivelog * ERROR at line 1: ORA-01126: database must be mounted in this instance and not open in any instance
日志归档必须在mount模式，关闭数据库启动到mount模式，开启归档模式：
SQL> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. SQL> startup mount; ORACLE instance started. Total System Global Area 1586708480 bytes Fixed Size 2213736 bytes Variable Size 1040189592 bytes Database Buffers 536870912 bytes Redo Buffers 7434240 bytes Database mounted. SQL> alter database archivelog; Database altered. SQL> alter database open; Database altered. SQL> archive log list; Database log mode Archive Mode Automatic archival Enabled Archive destination USE_DB_RECOVERY_FILE_DEST Oldest online log sequence 22 Next log sequence to archive 24 Current log sequence 24
使用RMAN联机备份数据库：
RMAN> backup as compressed backupset database plus archivelog delete all input;
使用备份集格式进行备份，并采用压缩的方式，压缩比例大概为5：1。备份数据文件，同时也备份归档日志文件，备份完成之后会将已经备份的归档日志文件从存储目录中删除，清除归档空间。
备份表空间：
RMAN> backup tablespace users; Starting backup at 06-NOV-17 using channel ORA_DISK_1 channel ORA_DISK_1: starting datafile copy input datafile file number=00004 name=/data/app/oracle/oradata/orcl/users01.dbf output file name=/data/app/oracle/test/ORCL/datafile/o1_mf_users_dzzxzmxv_.dbf tag=TAG20171106T134939 RECID=12 STAMP=959348980 channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:01 Finished backup at 06-NOV-17
使用压缩：
RMAN> backup as compressed backupset tablespace users;
使用RMAN备份数据文件，%U表示自动分配一个唯一的命名：
RMAN> backup as backupset datafile 1 format '/data/app/backup/datafile_1_%U';
清除命令，慎用
清除旧的备份文件set格式：
RMAN> delete obsolete; RMAN> crosscheck backupset; RMAN> delete expired backupset;
清楚旧的备份文件和所有备份，copy模式：
RMAN> list datafilecopy all; RMAN> delete expired backupcopy; RMAN> crosscheck datafilecopy all; RMAN> delete expired backupcopy;
如果是由于快闪恢复区容量限制，可以修改快闪恢复区的路径和容量：
SQL> alter system set db_recovery_file_dest='/data/app/oracle/test';
SQL> alter system set db_recovery_file_dest_size=10g;
RMAN增量备份
使用backup database时，都是全库备份，每次这样备份很耗时也占用磁盘空间，RMAN的增量备份就能解决这些问题。
这里有两种备份级别，级别0备份为全库备份，级别1的备份为增量备份，一般情况下需要对数据进行0级别的备份之后在进行级别1的增量备份。
RMAN> backup incremental level 0 database;
级别1的差异增量备份：
RMAN> backup incremental level 1 database;
对映像副本进行增量备份
RMAN> run {
2> backup incremental level 1 for recover of copy with tag 'incr_copy_backup' database;
3> recover copy of database with tag 'incr_copy_backup';
4> }
每次执行这条命令，就可以使用映像的方式对数据库进行增量备份。