通过RMAN有两种不同类型的备份方式：创建镜像复制和创建备份集。

备份集(Backup Sets)：

为RMAN默认备份选项。备份集是RMAN创建的具有特定格式的逻辑备份对象，备份集在逻辑上由一个或多个备份片段(Backup Piece)组成，每个备份片段在物理上对应一个操作系统文件，一个备份片段中可能包含多个数据文件、控制文件或归档文件，括弧之一。通过RMAN创建备份集的优势在于，备份时只读取数据库中已经使用的数据块，因此不管是从备份效率，或是节省存储空间的角度，创建备份集的方式都更有优势。

镜像复制(Image Copies)：

镜像复制实际上就是创建数据文件、控制文件或归档文件的备份文件，与用户通过操作系统命令创建的备份一样(甚至连执行的命令都相同，RMAN镜像复制使用COPY命令，Windows下复制文件也用COPY命令，Linux/UNIX下则是用cp命令)，只不过RMAN是利用目标数据库中的服务进程来完成文件复制，而用户则是用操作系统命令。这种方式本质仍是复制数据库中的物理文件，包括数据文件、控制文件等，复制出的文件与原始文件一模一样，所以镜像复制的方式体现不出RMAN的优势。

如何查看当前的备份方式

RMAN> show all;

using target database control file instead of recovery catalog

RMAN configuration parameters for database with db_unique_name PTIAN 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 'E:\APP\TIANPAN\PRODUCT\11.2.0\DBHOME_1\DATABASE\SNCFPTIAN.ORA'; # default

RMAN>

红色部分的配置说明当前的备份方式为备份集备份。

CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default

不改变RMAN的配置，也可以直接以镜像复制的方式备份，命令为：

RMAN>backup as copy database;

Starting backup at 08-JUL-15

allocated channel: ORA_DISK_1

channel ORA_DISK_1: SID=72 device type=DISK

channel ORA_DISK_1: starting datafile copy

input datafile file number=00001 name=E:\APP\TIANPAN\ORADATA\PTIAN\SYSTEM01.DBF

output file name=E:\APP\TIANPAN\FLASH_RECOVERY_AREA\PTIAN\DATAFILE\O1_MF_SYSTEM_BSTBH904_.DBF tag=TAG20150708T214720 RECID=2 STAMP=884555266

channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:35

channel ORA_DISK_1: starting datafile copy

input datafile file number=00002 name=E:\APP\TIANPAN\ORADATA\PTIAN\SYSAUX01.DBF

output file name=E:\APP\TIANPAN\FLASH_RECOVERY_AREA\PTIAN\DATAFILE\O1_MF_SYSAUX_BSTBJDFQ_.DBF tag=TAG20150708T214720 RECID=3 STAMP=884555292

channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:25

channel ORA_DISK_1: starting datafile copy

input datafile file number=00003 name=E:\APP\TIANPAN\ORADATA\PTIAN\UNDOTBS01.DBF

output file name=E:\APP\TIANPAN\FLASH_RECOVERY_AREA\PTIAN\DATAFILE\O1_MF_UNDOTBS1_BSTBK5V1_.DBF tag=TAG20150708T214720 RECID=4 STAMP=884555305

channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:07

channel ORA_DISK_1: starting datafile copy

input datafile file number=00005 name=E:\APP\TIANPAN\ORADATA\PTIAN\EXAMPLE01.DBF

output file name=E:\APP\TIANPAN\FLASH_RECOVERY_AREA\PTIAN\DATAFILE\O1_MF_EXAMPLE_BSTBKF80_.DBF tag=TAG20150708T214720 RECID=5 STAMP=884555312

channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:03

channel ORA_DISK_1: starting datafile copy

copying current control file

output file name=E:\APP\TIANPAN\FLASH_RECOVERY_AREA\PTIAN\CONTROLFILE\O1_MF_TAG20150708T214720_BSTBKJJC_.CTL tag=TAG20150708T214720 RECID=6 STAMP=884555313

channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:01

channel ORA_DISK_1: starting datafile copy

input datafile file number=00004 name=E:\APP\TIANPAN\ORADATA\PTIAN\USERS01.DBF

output file name=E:\APP\TIANPAN\FLASH_RECOVERY_AREA\PTIAN\DATAFILE\O1_MF_USERS_BSTBKKVB_.DBF tag=TAG20150708T214720 RECID=7 STAMP=884555314

channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:01

channel ORA_DISK_1: starting full datafile backup set

channel ORA_DISK_1: specifying datafile(s) in backup set

including current SPFILE in backup set

channel ORA_DISK_1: starting piece 1 at 08-JUL-15

channel ORA_DISK_1: finished piece 1 at 08-JUL-15

piece handle=E:\APP\TIANPAN\FLASH_RECOVERY_AREA\PTIAN\BACKUPSET\2015_07_08\O1_MF_NNSNF_TAG20150708T214720_BSTBKM7K_.BKP tag=TAG20150708T214720 comment=NONE

channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01

Finished backup at 08-JUL-15

RMAN>

当然你也可以修改RMAN的配置：

RMAN> CONFIGURE DEVICE TYPE DISK PARALLELISM 2 BACKUP TYPE TO COPY;

old RMAN configuration parameters:

CONFIGURE DEVICE TYPE DISK PARALLELISM 2 BACKUP TYPE TO BACKUPSET;

new RMAN configuration parameters:

CONFIGURE DEVICE TYPE DISK PARALLELISM 2 BACKUP TYPE TO COPY;

new RMAN configuration parameters are successfully stored

RMAN>

配置备份类型的命令：

To configure the default type of backup:

Start RMAN and connect to a target database and a recovery catalog (if used).

Configure backup sets or image copies as the default backup type.

The following examples configure the backup type for disk backups to copies and backup sets:CONFIGURE DEVICE TYPE DISK BACKUP TYPE TO COPY; # image copies

CONFIGURE DEVICE TYPE DISK BACKUP TYPE TO BACKUPSET; # uncompressed

The following examples configure compression for backup sets:CONFIGURE DEVICE TYPE DISK BACKUP TYPE TO COMPRESSED BACKUPSET;

CONFIGURE DEVICE TYPE sbt BACKUP TYPE TO COMPRESSED BACKUPSET;