How to relocate datafile from one drive to other without shutdown db

1. Login to SQL*Plus
2. Connect as SYS DBA with CONNECT / AS SYSDBA command
3. Make offline the affected tablespace

ALTER TABLESPACE tablespace_name OFFLINE;

4. Modify the name or location of datafiles in Oracle data dictionary using following command syntax:

ALTER TABLESPACE tablespace_name
RENAME DATAFILE 'fully qualified path to original data file name' 
TO 'new or original fully qualified path to new or original data file name';

5. Bring the tablespace online again

ALTER TABLESPACE tablespace_name ONLINE;

6. If you experienced this error : ORA-01113, execute this syntax:

recover datafile 'new fully qualified path to original data file name'

source : otn