RMAN备份恢复——备份集存储位置改变

如果数据文件或日志文件的位置发生了改变，那么有多种方法可以解决这个问题。比如使用ALTER DATABASE RENAME DATAFILE的方法，或者SET NEWNAME。

但是如果备份集的位置改变，Oracle在10g以前并没有提供相应的解决方法。

这篇文章介绍9i如何通过Oracle的DBMS_BACKUP_RESTORE包来实现这个功能。

在进行备份之前，检查备份表空间的信息：

SQL> SELECT FILE_ID, TABLESPACE_NAME FROM DBA_DATA_FILES WHERE TABLESPACE_NAME = 'USERS';

FILE_ID TABLESPACE_NAME
---------- ------------------------------
9 USERS

下面对表空间USERS进行备份：

$ rman target /

Recovery Manager: Release 9.2.0.4.0 - Production

connected to target database: MEMBER (DBID=1303377880)

RMAN> backup tablespace indx, info, users, tools;

Starting backup at 24-8月 -07
using target database controlfile instead of recovery catalog
configuration for DISK channel 2 is ignored
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=20 devtype=DISK
channel ORA_DISK_1: starting full datafile backupset
channel ORA_DISK_1: specifying datafile(s) in backupset
input datafile fno=00018 name=/data/oradata/member/info.dbf
input datafile fno=00009 name=/data/oradata/member/users01.dbf
input datafile fno=00006 name=/data/oradata/member/indx01.dbf
input datafile fno=00008 name=/data/oradata/member/tools01.dbf
channel ORA_DISK_1: starting piece 1 at 24-8月 -07
channel ORA_DISK_1: finished piece 1 at 24-8月 -07
piece handle=/data/backup/member/5siq6isk_1_1 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:45
Finished backup at 24-8月 -07

可以看到备份的输出备份集在/data/backup/member目录下，如果将备份通过操作系统转移到/data/backup目录下，则Oracle恢复的时候无法找到备份集，在9i及以前版本，Oracle也没有提供相应的命令来重定位这个备份集。

在操作系统级的解决方案是，建立一个文件连接ln，指向新的位置。如果要从Oracle方面解决这个问题，就只能使用DBMS_BACKUP_RESTORE包。

$ mv /data/backup/member/5siq6isk_1_1 /data/backup/
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$ rman target /

Recovery Manager: Release 9.2.0.4.0 - Production

connected to target database: MEMBER (DBID=1303377880)

RMAN> sql 'alter tablespace users offline';

using target database controlfile instead of recovery catalog
sql statement: alter tablespace users offline

RMAN> restore tablespace users;

Starting restore at 24-8月 -07

configuration for DISK channel 2 is ignored
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=11 devtype=DISK
channel ORA_DISK_1: starting datafile backupset restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
restoring datafile 00009 to /data/oradata/member/users01.dbf
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of restore command at 08/24/2007 13:17:23
ORA-19505: failed to identify file "/data/backup/member/5siq6isk_1_1"
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory