http://www.minovo.com/bbs/read.php?tid=253

增量备份的级别是一个0到4之间的整数。
增量备份有两种类型：差异型和累积型。
差异备份拷贝最近进行的同级或低级增量备份以来所有改变的数据块。当备份命令中使用了incremental关键字时，则默认使用差异备份作为增量备份的方式。
累积备份拷贝最近低级别增量备份以来的所有改变的数据块。
备份策略：
周日进行一次零级备份，周一、周二、周三进行二级备份；周四进行一级备份；周五、周六进行二级备份。
在执行备份的时候，我们考虑将数据文件的全备和归档日志备份分开执行，避免造成一些不必要的麻烦。在进行全备的时候，由于RAC的两个节点是共享的所有数据文件，控制文件，所以我们只连接其中的一个节点db1来进行备份。在进行归档日志的备份的时候，由于归档日志并非共享，而是在每个节点本地存储的，所以我们需要分别连接到两个节点进行归档日志的备份。
下面是详细的备份脚本：

零级备份脚本：
#!/bin/sh
# define env
export ORACLE_BASE=
export ORACLE_HOME=
export ORACLE_SID=
export PATH=
# 先登陆本地rman，再分配远程连接通道到rac节点db1，进行数据的零级备份
rman nocatalog target username/passwd ALLOCATE CHANNEL d1 DEVICE TYPE DISK CONNECT'username/passwd@db1';
ALLOCATE CHANNEL d2 DEVICE TYPE DISK CONNECT'username/passwd@db1';
backup incremental level 0 database tag 'fullbak_level0' format '/backup/back/full_level0_%U';
backup current controlfile format '/backup/back/control_bak_%T';
release CHANNEL d1 ;
release CHANNEL d2 ;
}
exit;
!EOF
# 先登陆本地rman，再分配远程连接通道，备份归档日志
rman nocatalog target username/passwd ALLOCATE CHANNEL d3 DEVICE TYPE DISK CONNECT'username/passwd@db1'format '/backup/back/ARC_rac1_%U';
ALLOCATE CHANNEL d4 DEVICE TYPE DISK CONNECT'username/passwd@db2'format '/backup/back/ARC_rac2_%U';
sql'alter system archive log current';
backup filesperset 3 archivelog all delete all input;
release channel d3;
release channel d4;
}
exit;
!

一级备份脚本：
#!/bin/sh
# define env
export ORACLE_BASE=
export ORACLE_HOME=
export ORACLE_SID=
export PATH=
# 先登陆本地rman，再分配远程连接通道到rac节点db1，进行数据的一级备份
rman nocatalog target username/passwd ALLOCATE CHANNEL d1 DEVICE TYPE DISK CONNECT'username/passwd@db1';
ALLOCATE CHANNEL d2 DEVICE TYPE DISK CONNECT'username/passwd@db1';
backup incremental level 1 database tag 'bak_level1' format '/backup/back/bak_level1_%U';
backup current controlfile format '/backup/back/control_bak_%T';
release CHANNEL d1 ;
release CHANNEL d2 ;
}
exit;
!EOF
# 先登陆本地rman，再分配远程连接通道，备份归档日志
rman nocatalog target username/passwd ALLOCATE CHANNEL d3 DEVICE TYPE DISK CONNECT'username/passwd@db1'format '/backup/back/ARC_rac1_%U';
ALLOCATE CHANNEL d4 DEVICE TYPE DISK CONNECT'username/passwd@db2'format '/backup/back/ARC_rac2_%U';
sql 'alter system archive log current';
backup filesperset 3 archivelog all delete all input;
release channel d3;
release channel d4;
}
exit;
!

二级备份脚本：
#!/bin/sh
# define env
export ORACLE_BASE=
export ORACLE_HOME=
export ORACLE_SID=
export PATH=
# 先登陆本地rman，再分配远程连接通道到rac节点db1，进行数据的二级备份
rman nocatalog target username/passwd ALLOCATE CHANNEL d1 DEVICE TYPE DISK CONNECT'username/passwd@db1';
ALLOCATE CHANNEL d2 DEVICE TYPE DISK CONNECT'username/passwd@db1';
backup incremental level 2 database tag 'bak_level2' format '/backup/back/bak_level1_%U';
backup current controlfile format '/backup/back/control_bak_%T';
release CHANNEL d1 ;
release CHANNEL d2 ;
}
exit;
!EOF
# 先登陆本地rman，再分配远程连接通道，备份归档日志
rman nocatalog target username/passwd ALLOCATE CHANNEL d3 DEVICE TYPE DISK CONNECT'username/passwd@db1'format '/backup/back/ARC_rac1_%U';
ALLOCATE CHANNEL d4 DEVICE TYPE DISK CONNECT'username/passwd@db2'format '/backup/back/ARC_rac2_%U';
sql 'alter system archive log current';
backup filesperset 3 archivelog all delete all input;
release channel d3;
release channel d4;
}
exit;