Oracle RMAN两种备份方式 – 备份集备份与镜像复制备份

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:

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

2. 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 copiesCONFIGURE 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;