在数据库人的圈子里，备份将是个永恒的话题。虽然对rman的原理知识并不陌生，但前不久为了给单位部署备份策略，还是消耗了我不少的脑细胞。制定完备份策略后，我们当然可以在rman中验证备份集的有效性，但是万一需要异机恢复呢，不知道我们有多少人在为了应对这10000/1的可能性而努力准备着。

--Rman 异机恢复实验

1、创建临时pfile

cd $ORACLE_HOME/dbs

cat init.ora | grep -v ^# | grep -v ^$ > initPROD.ora

[oracle@single01 dbs]$ cat inittx9ab.ora
db_name='TX9AB'
processes = 150
audit_trail ='db'
db_block_size=8192
db_domain=''
dispatchers='(PROTOCOL=TCP) (SERVICE=ORCLXDB)'
open_cursors=300
remote_login_passwordfile='EXCLUSIVE'
undo_tablespace='UNDOTBS1'
control_files = (/space/oradata/tx9ab/controlfile/control01.ctl,/space/oradata/tx9ab/controlfile/control02.ctl,/space/oradata/tx9ab/controlfile/control03.ctl,)
compatible ='11.2.0'
sga_target=200m
sga_max_size=200m

--利用临时的pfile启动实例

SQL> startup nomount
ORACLE instance started.

Total System Global Area  208769024 bytes
Fixed Size                  2226936 bytes
Variable Size              96470280 bytes
Database Buffers          104857600 bytes
Redo Buffers                5214208 bytes

2、还原spfile和controlfile

RMAN> restore spfile from '/space/backup/02qdob32_1_1';

Starting restore at 04-AUG-2015 09:58:12
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=20 device type=DISK
channel ORA_DISK_1: restoring spfile from AUTOBACKUP /space/backup/02qdob32_1_1
channel ORA_DISK_1: SPFILE restore from AUTOBACKUP complete
Finished restore at 04-AUG-2015 09:58:14

RMAN> shutdown immediate

using target database control file instead of recovery catalog
Oracle instance shut down

SQL> startup nomount
ORACLE instance started.

Total System Global Area  413372416 bytes
Fixed Size                  2228904 bytes
Variable Size             276827480 bytes
Database Buffers          130023424 bytes
Redo Buffers                4292608 bytes

RMAN> restore controlfile from '/space/backup/02qdob32_1_1';

Starting restore at 04-AUG-2015 10:01:26
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=20 device type=DISK

channel ORA_DISK_1: restoring control file
channel ORA_DISK_1: restore complete, elapsed time: 00:00:03
output file name=/space/oradata/tx9ab/controlfile/control01.ctl
output file name=/space/oradata/tx9ab/controlfile/control02.ctl
output file name=/space/oradata/tx9ab/controlfile/control03.ctl
Finished restore at 04-AUG-2015 10:01:29

RMAN> alter database mount;

database mounted
released channel: ORA_DISK_1

3、注册备份及信息

RMAN> catalog start with '/space/backup/';

searching for all files that match the pattern /space/backup/

List of Files Unknown to the Database
=====================================
File Name: /space/backup/01qdoatt_1_1
File Name: /space/backup/02qdob32_1_1

Do you really want to catalog the above files (enter YES or NO)? y
cataloging files...
cataloging done

List of Cataloged Files
=======================
File Name: /space/backup/01qdoatt_1_1
File Name: /space/backup/02qdob32_1_1

4、恢复数据库
--由于测试机的环境没有改变datafile的路径，可以直接还原

RMAN> run
 {allocate channel t1 type disk ;
 allocate channel t2 type disk ;
#set newname for database to '..../datafile/%b';
#set newname for tempfile 1 to '..../tempfile/%b';
restore database force;
 switch datafile all;
 release channel t1;
 release channel t2;}

RMAN> recover database;

Starting recover at 31-MAR-2015 00:01:52
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=20 device type=DISK

starting media recovery

unable to find archived log
archived log thread=1 sequence=1
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of recover command at 03/31/2015 00:01:52
RMAN-06054: media recovery requesting unknown archived log for thread 1 with sequence 1 and starting SCN of 2757245

RMAN> recover database until scn= 2757245;    -- 指定了scn ，丢掉了redo 中的日志信息；

SYS@tx9ab>alter database open resetlogs;

Database altered.

结论：

     由于异机恢复的场景里，一般是不会有联机日志的这里这里只能进行不完全恢复了！