随着版本不断地提升，RMAN作为标准备份工具的作用地位是不断的被增强的。从过去传统的备份还原工具，到现在新环境迁移、DG搭建，我们都可以看到RMAN工具增强的身影。
本篇就以RMAN为工具，利用RMAN备份在新主机上搭建服务名相同的数据库。由于环境所限，笔者采用的方法是：先进行备份获取，之后删除掉原数据库，最后使用备份重新搭建（包括参数、控制文件和数据文件恢复）。
1、环境介绍
我们选择Linux环境下的10.2.0.1进行实验。
SQL> select * from v$version;
BANNER
---------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prod
PL/SQL Release 10.2.0.1.0 - Production
CORE 10.2.0.1.0 Production
TNS for Linux: Version 10.2.0.1.0 - Production
NLSRTL Version 10.2.0.1.0 - Production
当前处在归档模式下。
SQL> archive log list;
Database log mode Archive Mode
Automatic archival Enabled
Archive destination USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence 2
Next log sequence to archive 4
Current log sequence 4
2、备份获取
RMAN支持online和offline两种备份模式。如果选择online备份模式，Oracle就不需要因为备份操作停机，但是恢复过程需要配合redo log的apply过程。如果选择offline备份模式，Oracle需要在备份过程中停机，但是理论上是不需要archive redo log进行支持的。
如果Oracle运行在archived模式下，RMAN可以进行online和offline模式。如果是noarchived模式，RMAN就只能在offline模式备份了。
当前环境变量：
[oracle@SimpleLinuxUp ~]$ env | grep ORA
ORACLE_SID=oratest
ORACLE_BASE=/u01/app/oracle
ORACLE_HOME=/u01/app/oracle/product/10.2.0/db_1
笔者对online和offline备份，都进行保留。首先创建驻留目录：
[root@SimpleLinuxUp ~]# cd /
[root@SimpleLinuxUp /]# mkdir onlinebk
[root@SimpleLinuxUp /]# mkdir oflinebk
[root@SimpleLinuxUp /]# chown oracle:oinstall onlinebk/
[root@SimpleLinuxUp /]# chown oracle:oinstall oflinebk/
[root@SimpleLinuxUp /]# ls -l | grep linebk
drwxr-xr-x 2 oracle oinstall 4096 Mar 3 16:46 oflinebk
drwxr-xr-x 2 oracle oinstall 4096 Mar 3 16:46 onlinebk
如果进行online备份，数据库不需要关闭。备份范围为：参数文件、数据文件、控制文件。
（online backup）
RMAN> connect target /
connected to target database: ORATEST (DBID=3370560176)
using target database control file instead of recovery catalog
RMAN> backup database format '/onlinebk/%U'; --数据库
Starting backup at 03-MAR-14
using channel ORA_DISK_1
channel ORA_DISK_1: starting full datafile backupset
(篇幅原因，有省略……)
piece handle=/onlinebk/04p28ubo_1_1 tag=TAG20140303T165227 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:02
Finished backup at 03-MAR-14
RMAN> backup archivelog all format '/onlinebk/%U'; --已经归档日志
Starting backup at 03-MAR-14
current log archived
using channel ORA_DISK_1
(篇幅原因，有省略……)
piece handle=/onlinebk/05p28uds_1_1 tag=TAG20140303T165420 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:02
Finished backup at 03-MAR-14
RMAN> backup current controlfile format '/onlinebk/control.bks';
Starting backup at 03-MAR-14
using channel ORA_DISK_1
(篇幅原因，有省略……)
piece handle=/onlinebk/control.bks tag=TAG20140303T165457 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 03-MAR-14
RMAN> backup spfile format '/onlinebk/spfile.bks';
Starting backup at 03-MAR-14
using channel ORA_DISK_1
(篇幅原因，有省略……)
piece handle=/onlinebk/spfile.bks tag=TAG20140303T165518 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 03-MAR-14
如果进行offline备份，则需要将数据库完整关闭（非abort关闭）。也不需要进行归档文件备份。
RMAN> shutdown immediate;
database closed
database dismounted
Oracle instance shut down
RMAN> startup mount;
connected to target database (not started)
Oracle instance started
database mounted
进行备份。
RMAN> backup database format '/oflinebk/%U';
Starting backup at 03-MAR-14
allocated channel: ORA_DISK_1
（篇幅原因，有省略……）
piece handle=/oflinebk/09p28ukd_1_1 tag=TAG20140303T165713 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:02
Finished backup at 03-MAR-14
RMAN> backup current controlfile format '/oflinebk/control.bks';
Starting backup at 03-MAR-14
using channel ORA_DISK_1
channel ORA_DISK_1: starting full datafile backupset
（篇幅原因，有省略……）
piece handle=/oflinebk/control.bks tag=TAG20140303T165824 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 03-MAR-14
RMAN> backup spfile format '/oflinebk/spfile.bks';
Starting backup at 03-MAR-14
using channel ORA_DISK_1
（篇幅原因，有省略……）
piece handle=/oflinebk/spfile.bks tag=TAG20140303T165841 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 03-MAR-14
必要的备份元素已经具备。注意：如果从完善的角度，对TNS网络参数三文件：tnsnames.ora、listener.ora和sqlnet.ora最好也进行备份。
3、数据库删除
配置XWindows工具调用dbca将原数据库删除。
[oracle@SimpleLinuxUp oflinebk]$ export DISPLAY=192.168.0.1:0.0
[oracle@SimpleLinuxUp oflinebk]$ xclock
Warning: Missing charsets in String to FontSet conversion
调用dbca删除数据库。
删除数据库确认。
SQL> conn / as sysdba
Connected to an idle instance.
SQL> startup
ORA-01078: failure in processing system parameters
LRM-00109: could not open parameter file '/u01/app/oracle/product/10.2.0/db_1/dbs/initoratest.ora'
注意：使用dbca删除数据库后，根据OFA原则创建的数据库目录大都被删除。相关文件也被删除。
下面就可以进行恢复过程。
4、参数文件恢复
参数文件是确保数据库进行nomount状态、实例创建、控制文件获取的重要文件。由于RMAN是工作在mount状态以上，所以需要先进行spfile的恢复。如果使用RMAN，是可以在没有参数文件的情况下，进入一个dummy数据库的。
RMAN> connect target /
connected to target database (not started)
MAN> startup nomount force;
startup failed: ORA-01078: failure in processing system parameters
LRM-00109: could not open parameter file '/u01/app/oracle/product/10.2.0/db_1/dbs/initoratest.ora'
starting Oracle instance without parameter file for retrival of spfile
Oracle instance started
Total System Global Area 159383552 bytes
Fixed Size 1218268 bytes
Variable Size 54528292 bytes
Database Buffers 100663296 bytes
Redo Buffers 2973696 bytes
恢复参数文件，使用restore spfile from ‘<目录>’方法。
RMAN> restore spfile from '/onlinebk/spfile.bks';
Starting restore at 03-MAR-14
using channel ORA_DISK_1
channel ORA_DISK_1: autobackup found: /onlinebk/spfile.bks
channel ORA_DISK_1: SPFILE restore from autobackup complete
Finished restore at 03-MAR-14
注意：这个时候还不能启动到nomount。
SQL> conn / as sysdba
Connected.
SQL> shutdown immediate
ORA-01507: database not mounted
ORACLE instance shut down.
SQL> startup nomount
ORA-09925: Unable to create audit trail file
Linux Error: 2: No such file or directory
Additional information: 9925
这个问题的原因在于：我们删除数据库之后，原有的很多与ORATEST相关的目录都被删除。解决的方法是利用文本格式的pfile确定目录，之后手工创建出来。
SQL> create pfile from spfile;
File created.
[oracle@SimpleLinuxUp ~]$ cd /u01/app/oracle/product/10.2.0/db_1/dbs/
[oracle@SimpleLinuxUp dbs]$ ls
hc_oratest.dat initdw.ora init.ora initoratest.ora snapcf_oratest.f spfileoratest.ora
参数文件initoratest.ora中，定义了很多目录结构，如control_files、recovery_file_dest等。内容较多，就不一一列举。手工使用mkdir进行创建。
[root@SimpleLinuxUp u01]# cd /
[root@SimpleLinuxUp /]# mkdir -p /u01/app/oracle/admin/oratest/adump
[root@SimpleLinuxUp /]# mkdir -p /u01/app/oracle/admin/oratest/bdump
[root@SimpleLinuxUp /]# mkdir -p /u01/app/oracle/oradata/ORATEST/controlfile/
[root@SimpleLinuxUp /]# mkdir -p /u01/app/oracle/flash_recovery_area/ORATEST/controlfile
[root@SimpleLinuxUp /]# mkdir -p /u01/app/oracle/flash_recovery_area/ORATEST/controlfile
[root@SimpleLinuxUp /]# mkdir -p /u01/app/oracle/admin/oratest/cdump
[root@SimpleLinuxUp /]# mkdir -p /u01/app/oracle/oradata
[root@SimpleLinuxUp /]# mkdir -p /u01/app/oracle/flash_recovery_area
[root@SimpleLinuxUp /]# mkdir -p /u01/app/oracle/admin/oratest/udump
[root@SimpleLinuxUp /]# chown -R oracle:oinstall /u01
[root@SimpleLinuxUp /]#
再尝试启动到nomount，成功。
SQL> conn / as sysdba
Connected to an idle instance.
SQL> startup nomount
ORACLE instance started.
Total System Global Area 247463936 bytes
Fixed Size 1218772 bytes
Variable Size 83887916 bytes
Database Buffers 159383552 bytes
Redo Buffers 2973696 bytes
5、控制文件恢复
使用restore controlfile from的方法进行控制文件恢复。
RMAN> restore controlfile from '/onlinebk/control.bks';
Starting restore at 03-MAR-14
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=431 devtype=DISK
channel ORA_DISK_1: restoring control file
channel ORA_DISK_1: restore complete, elapsed time: 00:00:02
output filename=/u01/app/oracle/oradata/ORATEST/controlfile/o1_mf_9k8lh412_.ctl
output filename=/u01/app/oracle/flash_recovery_area/ORATEST/controlfile/o1_mf_9k8lh45x_.ctl
Finished restore at 03-MAR-14
加载入control file之后，作为备份信息就可以读取到。
RMAN> report schema;
Starting implicit crosscheck backup at 03-MAR-14
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=431 devtype=DISK
Crosschecked 3 objects
Finished implicit crosscheck backup at 03-MAR-14
Starting implicit crosscheck copy at 03-MAR-14
using channel ORA_DISK_1
Finished implicit crosscheck copy at 03-MAR-14
searching for all files in the recovery area
cataloging files...
no files cataloged
RMAN-06139: WARNING: control file is not current for REPORT SCHEMA
Report of database schema
List of Permanent Datafiles
===========================
File Size(MB) Tablespace RB segs Datafile Name
---- -------- -------------------- ------- ------------------------
（篇幅原因，有省略……）
List of Temporary Files
=======================
File Size(MB) Tablespace Maxsize(MB) Tempfile Name
---- -------- -------------------- ----------- --------------------
1 0 TEMP 32767 /u01/app/oracle/oradata/ORATEST/datafile/o1_mf_temp_9cq625jt_.tmp
下面要讲/onlinebk目录中的备份加载进去，使用rman的catalog命令就可以实现这个功能。
RMAN> catalog start with '/onlinebk/';
searching for all files that match the pattern /onlinebk/
List of Files Unknown to the Database
=====================================
File Name: /onlinebk/spfile.bks
File Name: /onlinebk/control.bks
File Name: /onlinebk/02p28u13_1_1
Do you really want to catalog the above files (enter YES or NO)? yes
cataloging files...
cataloging done
List of Cataloged Files
=======================
File Name: /onlinebk/spfile.bks
File Name: /onlinebk/control.bks
File Name: /onlinebk/02p28u13_1_1
6、恢复数据文件
我们使用备份数据文件、归档文件和参数文件，在online状态下，是不能进行完全恢复的。因为运行状态下，当前active的日志信息是拿不到的。所以是需要进行until scn。
使用restore database preview可以查看当前可以做到什么程度。
RMAN> restore database preview ;
Starting restore at 03-MAR-14
using channel ORA_DISK_1
List of Backup Sets
===================
BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ ---------------
(篇幅原因，有省略……)
Key Thrd Seq S Low Time Name
------- ---- ------- - --------- ----
2 1 5 A 03-MAR-14 /u01/app/oracle/flash_recovery_area/ORATEST/archivelog/2014_03_03/o1_mf_1_5_9k8jsw0m_.arc
Media recovery start SCN is 556011
Recovery must be done beyond SCN 556011 to clear data files fuzziness
Finished restore at 03-MAR-14
进行数据库restore过程。
RMAN> restore database;
Starting restore at 03-MAR-14
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=434 devtype=DISK
channel ORA_DISK_1: starting datafile backupset restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
(篇幅原因，有省略……)
channel ORA_DISK_1: restored backup piece 1
piece handle=/onlinebk/03p28uab_1_1 tag=TAG20140303T165227
channel ORA_DISK_1: restore complete, elapsed time: 00:00:25
Finished restore at 03-MAR-14
尝试完全恢复。
RMAN> recover database;
Starting recover at 03-MAR-14
using channel ORA_DISK_1
starting media recovery
archive log thread 1 sequence 5 is already on disk as file /u01/app/oracle/flash_recovery_area/ORATEST/archivelog/2014_03_03/o1_mf_1_5_9k8jsw0m_.arc
archive log filename=/u01/app/oracle/flash_recovery_area/ORATEST/archivelog/2014_03_03/o1_mf_1_5_9k8jsw0m_.arc thread=1 sequence=5
unable to find archive log
archive log thread=1 sequence=6
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of recover command at 03/03/2014 17:34:43
RMAN-06054: media recovery requesting unknown log: thread 1 seq 6 lowscn 556089
恢复失败，只能选择恢复到有日志的SCN点。
RMAN> recover database until scn 556011;
Starting recover at 03-MAR-14
using channel ORA_DISK_1
starting media recovery
archive log thread 1 sequence 5 is already on disk as file /u01/app/oracle/flash_recovery_area/ORATEST/archivelog/2014_03_03/o1_mf_1_5_9k8jsw0m_.arc
archive log filename=/u01/app/oracle/flash_recovery_area/ORATEST/archivelog/2014_03_03/o1_mf_1_5_9k8jsw0m_.arc thread=1 sequence=5
media recovery complete, elapsed time: 00:00:00
Finished recover at 03-MAR-14
启动数据库，由于online redo log的缺失和指定SCN恢复，所以必须要进行resetlogs操作open数据库。
SQL> alter database open resetlogs;
Database altered.
[oracle@SimpleLinuxUp ~]$ ps -ef | grep pmon
oracle 3512 1 0 17:21 ? 00:00:00 ora_pmon_oratest
oracle 3639 3481 0 17:44 pts/0 00:00:00 grep pmon
7、结论和拓展
同名数据库同结构恢复是比较容易的。如果需要进行数据库名称修改，或者文件目录的修改，则需要进行额外的操作和步骤。但是无论是手工进行，还是虚拟搭建RMAN auxiliary数据库，这都是可以实现的。
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