使用RMAN验证备份的有效性

在完成备份之后，很多时候我们需要验证备份是否正常可用，存在于磁盘或磁带上的备份是否有效，RMAN提供的VALIDATE命令，可以帮助我们校验备份集的有效性，常用命令如下：

       restore validate controlfile;
       restore validate database;
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验证命令会检查备份的存在性、完好性和可恢复性，帮助我们确认备份的有效与否。比如验证控制文件和参数文件：

RMAN> restore validate controlfile;

Starting restore at 25-JAN-10
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=388 devtype=DISK

channel ORA_DISK_1: starting validation of datafile backupset
channel ORA_DISK_1: reading from backup piece /opt/oracle/product/db10g/dbs/c-1341966532-20100125-01
channel ORA_DISK_1: restored backup piece 1
piece handle=/opt/oracle/product/db10g/dbs/c-1341966532-20100125-01 tag=TAG20100125T094817
channel ORA_DISK_1: validation complete, elapsed time: 00:00:02
Finished restore at 25-JAN-10

RMAN> restore validate spfile;

Starting restore at 25-JAN-10
using channel ORA_DISK_1

channel ORA_DISK_1: starting validation of datafile backupset
channel ORA_DISK_1: reading from backup piece /opt/oracle/product/db10g/dbs/c-1341966532-20100116-00
channel ORA_DISK_1: restored backup piece 1
piece handle=/opt/oracle/product/db10g/dbs/c-1341966532-20100116-00 tag=TAG20100116T033113
channel ORA_DISK_1: validation complete, elapsed time: 00:00:02
Finished restore at 25-JAN-10
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验证全备份一般会很慢，具体时间与备份集大小有关：

RMAN> restore validate database;

Starting restore at 25-JAN-10
using channel ORA_DISK_1

data file 22 will be created automatically during restore operation
channel ORA_DISK_1: starting validation of datafile backupset
channel ORA_DISK_1: reading from backup piece /data3/ordrbak/orderfullback_order_20100124_4691
channel ORA_DISK_1: restored backup piece 1
piece handle=/data3/ordrbak/orderfullback_order_20100124_4691 tag=order
channel ORA_DISK_1: validation complete, elapsed time: 00:02:36
channel ORA_DISK_1: starting validation of datafile backupset
channel ORA_DISK_1: reading from backup piece /data3/ordrbak/orderfullback_order_20100124_4692
channel ORA_DISK_1: restored backup piece 1
piece handle=/data3/ordrbak/orderfullback_order_20100124_4692 tag=order
channel ORA_DISK_1: validation complete, elapsed time: 00:01:45
channel ORA_DISK_1: starting validation of datafile backupset
channel ORA_DISK_1: reading from backup piece /data3/ordrbak/orderfullback_order_20100124_4693
channel ORA_DISK_1: restored backup piece 1
piece handle=/data3/ordrbak/orderfullback_order_20100124_4693 tag=order
channel ORA_DISK_1: validation complete, elapsed time: 00:00:26
channel ORA_DISK_1: starting validation of datafile backupset
channel ORA_DISK_1: reading from backup piece /data3/ordrbak/orderfullback_order_20100124_4694
channel ORA_DISK_1: restored backup piece 1
piece handle=/data3/ordrbak/orderfullback_order_20100124_4694 tag=order
channel ORA_DISK_1: validation complete, elapsed time: 00:00:56
failover to previous backup

data file 22 will be created automatically during restore operation
Finished restore at 25-JAN-10
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验证命令并不会真正执行恢复，所以可以减去异机测试等的麻烦。
在11g中，备份集的验证可以在不同的粒度上进行，如验证文件、表空间、备份集、数据块等，命令参考如下：

validate backupset 2;
validate datafile 1 block 377;
validate tablespace <tablespace_name>;
validate database;
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