检测Oracle数据块损坏的方法汇总
使用初始化参数db_block_checksum\db_block_checking可以设置数据库对块的物理一致性和逻辑一致性检查。Db_block_checksum:物理一
1：使用初始化参数
使用初始化参数db_block_checksum\db_block_checking可以设置数据库对块的物理一致性和逻辑一致性检查。
Db_block_checksum:物理一致性检查，默认开启。始终对system表空间数据进行检查，如果开启还会对日志进行检查，开启后会有1～2%的性能影响，建议开启。
Db_block_checking：逻辑一致性检查，默认未开启。始终对system表空间进行检查，如果开启会有1～10%的性能影响。DML越频繁，性能影响越大。不建议开启。
有关该参数的详细内容可以参考：
2：使用dbv工具
使用dbv可以进行物理和逻辑一致性检查，但是不会检测表数据和索引数据的匹配关系。使用该工具有以下特点：
只读方式打开数据文件
可以在线检查数据文件，数据库无需关闭
不可以检测控制文件和日志文件
可以检测asm文件
有时文件名称需要有后缀名，并且有时不可以检测超过2G大小的文件
3：使用analyze命令
语法格式：analyze table validate structure cascade online (offline).
该命令会同时进行物理和逻辑检查，同时还可以进行表数据和索引数据的匹配性检查，检查分区表的记录是否在正确的分区中，检测结果会存储在trace文件中。
如果没有使用cascade关键字，则只会进行表数据的检测，使用cascade后会进行表数据和索引数据的检测。
如果使用了online关键字，则可以对表数据进行在线检查，此时不会对表添加锁，DML语句可以继续进行，如果使用了offline关键字，则会对表加锁，此时用户不能对该表进行修改操作。
如果需要检测分区表记录是否在正确的分区内，，可以使用如下语句：
Anlyze table table_name validte structure into invalid_rows.
使用该命令前，请使用utlvalid.sql 脚本创建相应的invalid_rows表。
--------------------------------------推荐阅读 --------------------------------------
RMAN 配置归档日志删除策略
Oracle基础教程之通过RMAN复制数据库
RMAN备份策略制定参考内容
RMAN备份学习笔记
Oracle数据库备份加密 RMAN加密
--------------------------------------分割线 --------------------------------------
4：使用rman工具
使用rman备份工具时，oracle会将数据先读入读缓冲区，然后将数据写入写缓冲区，最后写入磁盘，在从读缓冲区转移到写缓冲区时，rman工具会进行数据一致性检测。
语法格式：backup validate database.
使用backup validate 命令会对数据文件进行物理一致性检测（前提是db_block_checksum启用), 此时并不会生成备份文件。如：
RMAN> backup validate database;
Starting backup at 2014-11-05 15:44:21
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: 00:00:01
Finished backup at 2014-11-05 15:44:23
RMAN> list backup;
RMAN>
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