RMAN作为Oracle备份与恢复工具，为我们提供了强大的功能，其中包括对数据文件的物理和逻辑检测以及备份文件的有效性检测。
首先，来看一下RMAN对数据文件的检测。我们知道，RMAN在备份数据时，会将数据读入读缓存，然会将数据从读缓存写入写缓存并最终写入数据库。在从读缓存到写缓存的过程中，RMAN会进行物理一致性的检测（db_block_checksum未true）和逻辑一致性检测（使用了check logical选项）。例如：
SQL> show parameter db_block
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_block_buffers integer 0
db_block_checking string FALSE
db_block_checksum string TRUE
db_block_size integer 8192
SQL>
RMAN> backup tablespace test1;
Starting backup at 2014-11-06 15:12:49
using channel ORA_DISK_1
channel ORA_DISK_1: starting full datafile backupset
channel ORA_DISK_1: specifying datafile(s) in backupset
input datafile fno=00005 name=/home/app/oraten/oradata/oraten/test01.dbf
channel ORA_DISK_1: starting piece 1 at 2014-11-06 15:12:50
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03009: failure of backup command on ORA_DISK_1 channel at 11/06/2014 15:12:51
ORA-19566: exceeded limit of 0 corrupt blocks for file /home/app/oraten/oradata/oraten/test01.dbf
有时，我们仅仅希望验证一下数据文件是否可以备份，而不想进行真正的备份，这是我们就可以使用validate命令了，如
RMAN> backup validate database;
Starting backup at 2014-11-06 15:14:23
using channel ORA_DISK_1
channel ORA_DISK_1: starting full datafile backupset
channel ORA_DISK_1: specifying datafile(s) in backupset
input datafile fno=00001 name=/home/app/oraten/oradata/oraten/system01.dbf
input datafile fno=00003 name=/home/app/oraten/oradata/oraten/sysaux01.dbf
input datafile fno=00002 name=/home/app/oraten/oradata/oraten/undotbs01.dbf
input datafile fno=00005 name=/home/app/oraten/oradata/oraten/test01.dbf
input datafile fno=00004 name=/home/app/oraten/oradata/oraten/users01.dbf
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
channel ORA_DISK_1: starting full datafile backupset
channel ORA_DISK_1: specifying datafile(s) in backupset
including current control file in backupset
including current SPFILE in backupset
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:03
Finished backup at 2014-11-06 15:14:27
注意，这里并没有发现test01.dbf的物理损坏块，个人认为，rman仅仅只是将数据文件读入了读缓存，而没有进行下面的操作，也就是说对于物理块的检测其功能是有限的，但，我们可以用其来检测物理文件的可读性和位置等。
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