db_create_file_dest string
主库做操作：
SQL> create tablespace test4 datafile '+DG1/dg/datafile/test4.dbf' size 10m;
Tablespace created.
SQL> create tablespace test5 datafile '+DG2/dg/datafile/test5.dbf' size 10m;
Tablespace created.
SQL> select * from v$dbfile;
FILE# NAME
---------- --------------------------------------------------
1 +DG1/dg/datafile/system.260.852134271
2 +DG1/dg/datafile/sysaux.261.852134303
3 +DG1/dg/datafile/undotbs1.262.852134329
4 +DG1/dg/datafile/users.264.852134361
5 +DG2/dg/datafile/test1.dbf
6 +DG2/dg/datafile/test2.dbf
7 +DG1/dg/datafile/test4.dbf
8 +DG2/dg/datafile/test5.dbf
备库做查询：
SQL> select * from v$dbfile;
FILE# NAME
---------- --------------------------------------------------
1 +DG1/dg2/datafile/system.258.852146097
2 +DG1/dg2/datafile/sysaux.257.852146099
3 +DG1/dg2/datafile/undotbs1.256.852146101
4 +DG1/dg2/datafile/users.259.852146107
5 +DG2/dg/datafile/test1.dbf
6 +DG1/dg2/datafile/test2.272.852147911
7 +DG1/dg/datafile/test4.dbf
8 +DG2/dg/datafile/test5.dbf
三、观察下ASM磁盘组中对于数据文件别名的存储形式
ASMCMD> ls -al
WARNING:option 'a' is deprecated for 'ls'
please use 'absolutepath'
Type Redund Striped Time Sys Name
DATAFILE UNPROT COARSE JUL 05 22:00:00 Y none => SYSAUX.257.852146099
DATAFILE UNPROT COARSE JUL 05 22:00:00 Y none => SYSTEM.258.852146097
DATAFILE UNPROT COARSE JUL 05 22:00:00 Y none => TEST2.272.852147911
DATAFILE UNPROT COARSE JUL 05 22:00:00 Y +DG1/dg/datafile/test4.dbf => TEST4.279.852157365
DATAFILE UNPROT COARSE JUL 05 22:00:00 Y none => UNDOTBS1.256.852146101
DATAFILE UNPROT COARSE JUL 05 22:00:00 Y none => USERS.259.852146107
ASMCMD> ls -al
WARNING:option 'a' is deprecated for 'ls'
please use 'absolutepath'
Type Redund Striped Time Sys Name
DATAFILE UNPROT COARSE JUL 05 22:00:00 Y +DG2/dg/datafile/test1.dbf => TEST1.256.852146103
DATAFILE UNPROT COARSE JUL 05 22:00:00 Y +DG2/dg/datafile/test5.dbf => TEST5.260.852157413
四、为ASM中SYSTEM表空间使用别名
比如上面创建的表空间test4其对应的数据文件TEST4.DBF是一个别名，真实的数据文件与别名的对应是：+DG1/dg/datafile/test4.dbf => TEST4.279.852157365
，然而(system,undotbs,sysaux,users)对应的都是真实的数据文件，没有别名，这时如果要对这些表空间使用别名，就需要重建控制文件。示例如下：
alter diskgroup dg1 add alias '+DG1/dg2/datafile/SYSTEM1.DBF' FOR '+DG1/dg2/datafile/system.258.852146097';
此时ASMCMD中查看：
ASMCMD> ls -al
WARNING:option 'a' is deprecated for 'ls'
please use 'absolutepath'
Type Redund Striped Time Sys Name
DATAFILE UNPROT COARSE JUL 05 23:00:00 Y none => SYSAUX.257.852146099
DATAFILE UNPROT COARSE JUL 05 23:00:00 Y +DG1/DG2/DATAFILE/SYSTEM1.DBF => SYSTEM.258.852146097
N SYSTEM1.DBF => +DG1/DG2/DATAFILE/SYSTEM.258.852146097
SQL> startup nomount;
ORACLE instance started.
Total System Global Area 418484224 bytes
Fixed Size 1365040 bytes
Variable Size 255855568 bytes
Database Buffers 155189248 bytes
Redo Buffers 6074368 bytes
SQL> CREATE CONTROLFILE REUSE DATABASE "DG" RESETLOGS FORCE LOGGING ARCHIVELOG …………
重建控制文件完成后数据库是MOUNT状态，此时查询：
SQL> select * from v$dbfile;
FILE# NAME
---------- --------------------------------------------------
8 +DG2/dg/datafile/test5.dbf
7 +DG1/dg/datafile/test4.dbf
6 +DG1/dg2/datafile/test2.272.852147911
5 +DG2/dg/datafile/test1.dbf
4 +DG1/dg2/datafile/users.259.852146107
3 +DG1/dg2/datafile/undotbs1.256.852146101
2 +DG1/dg2/data