ORA-15260 error comes when you try to drop an ASM diskgroup while connecting as SYSDBA.
SQL> drop diskgroup DATA;
drop diskgroup DATA
*
ERROR at line 1:
ORA-15260: permission denied on ASM disk group
Note : - As we all know that only one ASM instance is required to run multiple databases on a single server so if we have logged in one of the database with sysdba that is associated with that ASM instance and try to drop a disk group which is being used by other databases as well then oracle will not let that happen and throws above error (Suppose if diskgroup gets droped by SYSDBA having connected with one of the database then what would happen to other databases when underlying storage media is not available?) .
So, Oracle 11g onward, oracle requires SYSASM privilege do CREATE or DROP an ASM diskgroup.
let's connect SYS as SYSASM and try to drop the ASM diskgroup now.
SQ> conn /as sysasm
Connected.
SQL> drop diskgroup DATA including contents;
Diskgroup dropped.
SQL> drop diskgroup FRA including contents;
Diskgroup dropped.
Note:- Now you can see diskgroups are dropped being connected with sysasm.
Feel free to contact if any confusion.
