RMAN 恢复实践

谈恢复肯定离不开备份，不过今天我们的重点不在于此，我在在这里将备份分为两类：操作系统备份和数据库备份，而数据库备份工作我们大部分都是用RMAN 来做。对于使用RMAN 我强烈建议使用catalog mode。

测试环境：WIN2K ADV+ORACLE817

RMAN：target database named ORA，catalog database named RCVDB

一、Control file的恢复

说明：RMAN 的备份必须在catalog mode下进行，否则备份了control file也没有用；但即使是这样有时候可能还会出现很多问题。建议：control file 用SQL或操作系统的方式做备份和恢复。

1、RMAN备份的恢复

备份：

run {

allocate channel c1 type disk;

backup current controlfile;

}

恢复：

run {

allocate channel c1 type disk;

restore controlfile to '/oracle/oradata/ora/control01.ctl';

replicate controlfile from '/oracle/oradata/ora/control01.ctl';

restore database;

sql 'alter database mount';

recover database until cancel;

sql 'alter database open resetlogs';

release channel c1;

}

使用resetlogs之后需在catalog database 上进行reset database，原有备份信息将不可用，所以要及时进行新的完全备份。

2、SQL备份的恢复

备份：

alter database backup controlfile to trace;

恢复：

先将数据库shutdown，然后从备份所产生的trace文件中拷出创建恢复所用的SQL执行一遍

即可。如果你之前没有做这样的备份那也没关系，形式如下你可以照着写一个：

#--------------------------------BEGIN-----------------------------------------


# The following commands will create a new control file and use it

# to open the database.

# Data used by the recovery manager will be lost. Additional logs may

# be required for media recovery of offline data files. Use this

# only if the current version of all online logs are available.

STARTUP NOMOUNT

CREATE CONTROLFILE REUSE DATABASE "ORA" NORESETLOGS

NOARCHIVELOG

MAXLOGFILES 32

MAXLOGMEMBERS 2

MAXDATAFILES 32

MAXINSTANCES 16

MAXLOGHISTORY 680

LOGFILE

GROUP 1 (

'C:\ORACLE\ORADATA\ORA\REDO01.LOG',

'C:\ORACLE\ORADATA\ORA\REDO01_1.LOG'

) SIZE 1M,

GROUP 2 (

'C:\ORACLE\ORADATA\ORA\REDO02.LOG',

'C:\ORACLE\ORADATA\ORA\REDO02_1.LOG'

) SIZE 1M,

GROUP 3 (

'C:\ORACLE\ORADATA\ORA\REDO03_1.LOG',

'C:\ORACLE\ORADATA\ORA\REDO03_2.LOG'

) SIZE 1M

DATAFILE

'C:\ORACLE\ORADATA\ORA\SYSTEM01.DBF',

'C:\ORACLE\ORADATA\ORA\RBS01.DBF',

'C:\ORACLE\ORADATA\ORA\USERS01.DBF',

'C:\ORACLE\ORADATA\ORA\TEMP01.DBF',

'C:\ORACLE\ORADATA\ORA\TOOLS01.DBF',

'C:\ORACLE\ORADATA\ORA\INDX01.DBF'

CHARACTER SET ZHS16GBK
;

# Recovery is required if any of the datafiles are restored backups,

# or if the last shutdown was not normal or immediate.

RECOVER DATABASE

# Database can now be opened normally.

ALTER DATABASE OPEN;

3、OS 备份的恢复

备份：

OS copy

恢复：

OS copy回来即可，要注意的是这个备份必须是最新有效的。

二、Database的恢复

A、To restore the database from host_a to host_b with the same file system

#此处使用recovery catalog；

#如果不是catalog mode，就用OS COPY直接将control file

#copy过来并mount database。

1、copy the init.ora file from host_a to host_b using o/s utility

2、rman target sys/sys@host_b catalog rman/rman@rcat

3、startup nomount

4、run {

allocate channel c1 type disk;

restore controlfile;

sql ‘alter database mount’;

}

5、select min(scn) from (

select max(next_change#) scn from v$archived_log

group by thread#);

6、run {

set until scn=500; #use appropriate SCN for incomplete recovery

allocate channel c1 type ‘sbt_type’;

restore database;

recover database;

sql ‘alter database open resetlogs’;

}

B、To restore the database from host_a to host_b with a different filesystem

步骤和A差不多，不同的是在启动数据库之前要修改init.ora文件中所有和路径相关的参数，

如：*_DEST，*_PATH 等。然后执行如下脚本：

run {

set until scn=500;

allocate channel c1 type disk;

set newname for datafile 1 to ‘/disk’/%U’;

set newname for datafile 2 to ‘/disk’/%U’;

set newname for datafile 3 to ‘/disk’/%U’;

set newname for datafile 4 to ‘/disk’/%U’;

set newname for datafile 5 to ‘/disk’/%U’;

set newname for datafile 6 to ‘/disk’/%U’;

set newname for datafile 7 to ‘/disk’/%U’;

sql ‘alter database mount’;

restore database;

switch datafile all; #points the control file to the renamed datafiles

recover database;
.... ....

sql ‘alter database open resetlogs’;

}

三、Tablespace and datafile的恢复

run {

allocate channel c1 type disk;

sql ‘alter tablespace users offline immediate’; #must be in archive log mode

#如下改变datafile位置

set newname for datafile 'c:/oracle/oradata/ora/users01.dbf'

to 'c:/oracle/oradata/orabk/user01.dbf';

restore tablespace users;

switch datafile all;

recover tablespace users;

sql ‘alter tablespace users online’;

}

如果不在archive log mode下，执行以上SQL时会出错：ORA-01145。你将不得不shutdown。

四、关于set until 选项

set until后面可以跟time、scn和logseq三个不同的选项，当数据库运行在noarchivelog

mode 下时可以使用until cancel选项进行数据库的不完全恢复。所有这些的具体过程和以上的数据库恢复都差不多，不再赘述。