--查看当前情况
SQL> select count(*) from hr.a;
  COUNT(*)
----------
      1580
SQL>  select name from v$DATAFILE;
NAME
-----------------------------------------------------------
+DATA/tasm/system01.dbf
+DATA/tasm/undotbs01.dbf
+DATA/tasm/sysaux01.dbf
+DATA/tasm/users01.dbf
+DATA/tasm/example01.dbf
+DG2/tasm/datafile/xff.256.754902279
6 rows selected.
--创建目录
SQL>  create directory asmsrc as '+DG2/TASM/datafile';
Directory created.
SQL>  create directory osdesc as '/u01/oradata';
Directory created.
--表空间离线
SQL> alter tablespace xff offline;
Tablespace altered.
--数据文件迁移
SQL> begin
  2      dbms_file_transfer.copy_file('ASMSRC',
  3      'xff.256.754902279',
  4      'OSDESC',
  5      'xff_new_2.dbf');
  6  END;
  7  /
PL/SQL procedure successfully completed.
--修改数据库中datafile路径
SQL> alter database rename file
  2             '+DG2/tasm/datafile/xff.256.754902279'
  3             to '/u01/oradata/xff_new_2.dbf';
Database altered.
--表空间在线
SQL> alter tablespace xff online;
Tablespace altered.
--测试迁移结果
SQL> select name from v$DATAFILE;
NAME
-------------------------------------------------------------------
+DATA/tasm/system01.dbf
+DATA/tasm/undotbs01.dbf
+DATA/tasm/sysaux01.dbf
+DATA/tasm/users01.dbf
+DATA/tasm/example01.dbf
/u01/oradata/xff_new_2.dbf
6 rows selected.
SQL> select count(*) from hr.a;
  COUNT(*)
----------
      1580
--删除asm中文件
ASMCMD> rm XFF.256.754902279
ORA-15032: not all alterations performed
ORA-15028: ASM file '+dg2/tasm/datafile/XFF.256.754902279' not dropped;
currently being accessed (DBD ERROR: OCIStmtExecute)
--不能直接删除，关闭数据库后可以删除（应该是bug）