1.使用rman，对users表空间，做镜像备份
backup as copy tablespace users;
2.在数据库中，查询users表空间所对应的数据文件
select TABLESPACE_NAME,FILE_NAME from dba_data_files where TABLESPACE_NAME='USERS';
TABLESPACE_NAME FILE_NAME
------------------------------ --------------------------------------------------
USERS /u01/app/oracle/oradata/orcl/users01.dbf
删除，模拟故障
SQL> !rm -rf /u01/app/oracle/oradata/orcl/users01.dbf
ORA-01157: cannot identify/lock data file 4 - see DBWR trace file
ORA-01110: data file 4: '/u01/app/oracle/oradata/orcl/users01.dbf'
使该文件offline，准备恢复
alter database datafile 4 offline;
3.在rman中，使用快速镜像恢复
RMAN> switch datafile 4 to copy;
using target database control file instead of recovery catalog
datafile 4 switched to datafile copy "/u02/ORCL/datafile/o1_mf_users_cnbqw6f6_.dbf"
RMAN> recover datafile 4;
Starting recover at 25-MAY-16
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=5 device type=DISK
starting media recovery
media recovery complete, elapsed time: 00:00:00
Finished recover at 25-MAY-16
4.数据库中使该文件online
alter database datafile 4 online;
5.在数据库查看当前所有的数据文件
SQL> select name from v$datafile;
NAME
-------------------------------------------------------
/u01/app/oracle/oradata/orcl/system01.dbf
/u01/app/oracle/oradata/orcl/sysaux01.dbf
/u01/app/oracle/oradata/orcl/undotbs01.dbf
/u02/ORCL/datafile/o1_mf_users_cnbqw6f6_.dbf
/u01/app/oracle/oradata/orcl/example01.dbf
发现users表空间，实际使用的数据文件，变成了，我们之前做的镜像备份文件
如果看着别扭，想变成原来的样子
再来一次镜像备份与快速镜像恢复
6.在rman中，使用镜像备份，指定备份的位置是该数据文件被删除之前的位置及文件名
RMAN> backup as copy datafile 4 format '/u01/app/oracle/oradata/orcl/users01.dbf';
Starting backup at 25-MAY-16
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=5 device type=DISK
channel ORA_DISK_1: starting datafile copy
input datafile file number=00004 name=/u02/ORCL/datafile/o1_mf_users_cnbqw6f6_.dbf
output file name=/u01/app/oracle/oradata/orcl/users01.dbf tag=TAG20160525T162240 RECID=8 STAMP=912788561
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:01
Finished backup at 25-MAY-16
Starting Control File and SPFILE Autobackup at 25-MAY-16
piece handle=/u02/ORCL/autobackup/2016_05_25/o1_mf_s_912788561_cnbr6kx1_.bkp comment=NONE
Finished Control File and SPFILE Autobackup at 25-MAY-16
7.在数据库中，offline datafile 4
SQL> alter database datafile 4 offline;
Database altered.
8.在rman中，执行快速镜像恢复
RMAN> switch datafile 4 to copy;
datafile 4 switched to datafile copy "/u01/app/oracle/oradata/orcl/users01.dbf"
RMAN> recover datafile 4;
Starting recover at 25-MAY-16
using channel ORA_DISK_1
starting media recovery
media recovery complete, elapsed time: 00:00:00
Finished recover at 25-MAY-16
9.在数据库，Online datafile 4
SQL> alter database datafile 4 online;
Database altered.
再次查询数据文件，发现变回原来的文件名了
SQL> select name from v$datafile;
NAME
---------------------------------------------------------------------------------------------
/u01/app/oracle/oradata/orcl/system01.dbf
/u01/app/oracle/oradata/orcl/sysaux01.dbf
/u01/app/oracle/oradata/orcl/undotbs01.dbf
/u01/app/oracle/oradata/orcl/users01.dbf
/u01/app/oracle/oradata/orcl/example01.dbf