深入解析Oracle：数据库的初始化
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2.7 文件系统与ASM的切换

在进行表空间迁移时，如果是从文件系统到文件系统的迁移很容易实现，但是如果是从文件系统到ASM则需要多一点步骤。类似前面的测试，如果在ASM环境中执行同样的导入命令：

imp \'/ as sysdba\' tablespaces=trans transport_tablespace=y

file=exp_trans.dmp datafiles=/opt/oracle/trans.dbf

则简单地导入之后会出现如下的效果，新导入的文件位于文件系统之上，这显然是不希望看到的，我们需要将文件系统文件转移到ASM磁盘组上去：

SQL> select name from v$datafile;

NAME

--------------------------------------------------------------------------------

+DATADG/rac/datafile/system.259.722961061

+DATADG/rac/datafile/undotbs1.260.722961083

+DATADG/rac/datafile/sysaux.261.722961087

+DATADG/rac/datafile/undotbs2.263.722961097

+DATADG/rac/datafile/users.264.722961099

/opt/oracle/trans.dbf

文件转移可以通过RMAN来进行，但是首次尝试遇到了RMAN-20201错误：

[oracle@rac1 oracle]$ rman target /

Recovery Manager: Release 10.2.0.4.0 - Production on Wed Sep 1 14:24:37 2010

Copyright (c) 1982, 2007, Oracle. All rights reserved.

connected to target database: RAC (DBID=2310943069)

RMAN> backup as copy datafile '/opt/oracle/trans.dbf' format '+DATADG';

Starting backup at 01-SEP-10

using target database control file instead of recovery catalog

allocated channel: ORA_DISK_1

channel ORA_DISK_1: sid=124 instance=rac1 devtype=DISK

RMAN-00571: ===========================================================

RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============

RMAN-00571: ===========================================================

RMAN-03002: failure of backup command at 09/01/2010 14:25:21

RMAN-20201: datafile not found in the recovery catalog

RMAN-06010: error while looking up datafile: /opt/oracle/trans.dbf

这个错误是由于 TRANS 表空间刚刚导入数据库中，处于只读状态，并未被 Catalog 记录感知，通过对这个文件进行特定操作，如读写变更，则可以消除此错误：

SQL> select tablespace_name,status from dba_tablespaces where tablespace_name=’TRANS’;

TABLESPACE_NAME　STATUS

------------------------------ ---------

TRANS　READ ONLY

RMAN中的Schema信息尚未记录该表空间：

RMAN> report schema;

Report of database schema

List of Permanent Datafiles

===========================

File　Size(MB)　Tablespace　RB segs　Datafile Name

---- -------- ---------------- -------- ------------------------------------

1　300　SYSTEM　***　+DATADG/rac/datafile/system.259.722961061

2　200　UNDOTBS1　***　+DATADG/rac/datafile/undotbs1.260.722961083

3　280　SYSAUX　***　+DATADG/rac/datafile/sysaux.261.722961087

4　200　UNDOTBS2　***　+DATADG/rac/datafile/undotbs2.263.722961097

5　5　USERS　***　+DATADG/rac/datafile/users.264.722961099

6　512　STREAM_TBS　***　+DATADG/rac/datafile/stream_tbs.268.725126097

7　1　TESTTBS1　***　+DATADG/rac/datafile/testtbs1.269.726592535

List of Temporary Files

=======================

File　Size(MB)　Tablespace　Maxsize(MB)　Tempfile Name

---- -------- ------------------ ----------- --------------------

1　20　TEMP　32767　+DATADG/rac/tempfile/temp.262.722961089

在数据库内部对该表空置读写访问：

SQL> alter tablespace trans read write;

Tablespace altered.

然后可以看到该表空间被Catalog所记录，当然这里的信息是来自控制文件的：

RMAN> report schema;

using target database control file instead of recovery catalog

Report of database schema

List of Permanent Datafiles

===========================

File　Size(MB)　Tablespace　RB segs　Datafile Name

---- -------- ------------------ --------- ------------------------

1　300　SYSTEM　***　+DATADG/rac/datafile/system.259.722961061

2　200　UNDOTBS1　***　+DATADG/rac/datafile/undotbs1.260.722961083

3　280　SYSAUX　***　+DATADG/rac/datafile/sysaux.261.722961087

4　200　UNDOTBS2　***　+DATADG/rac/datafile/undotbs2.263.722961097

5　5　USERS　***　+DATADG/rac/datafile/users.264.722961099

6　512　STREAM_TBS　***　+DATADG/rac/datafile/stream_tbs.268.725126097

7　1　TESTTBS1　***　+DATADG/rac/datafile/testtbs1.269.726592535

8　10　TRANS　***　/opt/oracle/trans.dbf

List of Temporary Files

=======================

File　Size(MB)　Tablespace　Maxsize(MB)　Tempfile Name

---- -------- -------------------- ----------- --------------------

1　20　TEMP　32767　+DATADG/rac/tempfile/temp.262.722961089

接下来将表空间状态再改为只读：

SQL> alter tablespace trans read only;

Tablespace altered.

通过RMAN进行镜像拷贝：

RMAN> backup as copy datafile '/opt/oracle/trans.dbf' format '+DATADG';

Starting backup at 01-SEP-10

using target database control file instead of recovery catalog

allocated channel: ORA_DISK_1

channel ORA_DISK_1: sid=130 instance=rac1 devtype=DISK

channel ORA_DISK_1: starting datafile copy

input datafile fno=00008 name=/opt/oracle/trans.dbf

output filename=+DATADG/rac/datafile/trans.270.728577593 tag=TAG20100901T143951 recid=2 stamp=728577592

channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:01

Finished backup at 01-SEP-10

切换之前需要将表空间离线，否则会出现错误：

RMAN> switch datafile '/opt/oracle/trans.dbf' to copy;

RMAN-00571: ===========================================================

RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============

RMAN-00571: ===========================================================

RMAN-03002: failure of switch to copy command at 09/01/2010 14:40:58

RMAN-06572: database is open and datafile 8 is not offline

将表空间离线：

SQL> alter tablespace trans offline;

Tablespace altered.

执行切换：

RMAN> switch datafile '/opt/oracle/trans.dbf' to copy;

datafile 8 switched to datafile copy "+DATADG/rac/datafile/trans.270.728577593"

现在转换后的表空间已经被转移到了ASM磁盘组中，此时可以将表空间Online，如果操作期间有过事务变更，还可能需要恢复：

SQL> alter tablespace trans online;

Tablespace altered.

SQL> select name from v$datafile;

NAME

--------------------------------------------------------------------------------

+DATADG/rac/datafile/system.259.722961061

+DATADG/rac/datafile/undotbs1.260.722961083

+DATADG/rac/datafile/sysaux.261.722961087

+DATADG/rac/datafile/undotbs2.263.722961097

+DATADG/rac/datafile/users.264.722961099

+DATADG/rac/datafile/trans.270.728577593

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