ORA-15030: diskgroup name "string" is in use by another diskgroup
Cause : A CREATE DISKGROUP command specfied a diskgroup name that was already assigned to another diskgroup.
Action - How to fix it : DBA Scripts :: www.high-oracle.com/scripts
Select a different name for the diskgroup.
Well, the reason for above error is that i have taken the above script from a 11g database and running it on 10g database. 11g has bring some changes in password management. Below code is executed on 11g and user created successfully, which is expected result.