11g active data guard实现备库rman备份，这样可以在不影响主库对外服务的情况下，实现数据库的备份。
测试如下：
SQL> select OPEN_MODE,PROTECTION_MODE,PROTECTION_LEVEL,DATABASE_ROLE from v$database;
OPEN_MODE PROTECTION_MODE PROTECTION_LEVEL DATABASE_ROLE
-------------------- -------------------- -------------------- ----------------
READ ONLY WITH APPLY MAXIMUM AVAILABILITY MAXIMUM AVAILABILITY PHYSICAL STANDBY
Recovery Manager: Release 11.2.0.3.0 - Production on Tue Mar 4 17:01:40 2014
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
connected to target database: VCM01 (DBID=1142584794)
RMAN> backup database;
Starting backup at 04-MAR-14
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=2280 device type=DISK
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00005 name=/datafile/vcm01/htz_data01.dbf
input datafile file number=00002 name=/datafile/vcm01/sysaux01.dbf
input datafile file number=00008 name=/datafile/vcm01/vats_dat01.dbf
input datafile file number=00004 name=/datafile/vcm01/dba_ts01.dbf
input datafile file number=00001 name=/datafile/vcm01/system01.dbf
input datafile file number=00006 name=/datafile/vcm01/htz_index01.dbf
input datafile file number=00003 name=/datafile/vcm01/undotbs01.dbf
input datafile file number=00007 name=/datafile/vcm01/user_ts_moni_11b01.dbf
input datafile file number=00009 name=/datafile/vcm01/user_ts_moni_12b01.dbf
input datafile file number=00010 name=/datafile/vcm01/user_ts_moni_13a01.dbf
channel ORA_DISK_1: starting piece 1 at 04-MAR-14
channel ORA_DISK_1: finished piece 1 at 04-MAR-14
piece handle=/flashbackfile/vcm01/VCM01_B/backupset/2014_03_04/o1_mf_nnndf_TAG20140304T170146_9kc5mv98_.bkp tag=TAG20140304T170146 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:25
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current control file in backup set
including current SPFILE in backup set
channel ORA_DISK_1: starting piece 1 at 04-MAR-14
channel ORA_DISK_1: finished piece 1 at 04-MAR-14
piece handle=/flashbackfile/vcm01/VCM01_B/backupset/2014_03_04/o1_mf_ncsnf_TAG20140304T170146_9kc5nofm_.bkp tag=TAG20140304T170146 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 04-MAR-14
RMAN>
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