Oracle Solution for Error ora-15201

ORA-15201: disk string contains a valid RDBMS file

What triggered the Error:

A disk specified in a CREATE DISKGROUP or ALTER DISKGROUP ... ADD DISK command appeared to contain a file from an existing database. By default, ASM will not allow a diskgroup to be created using this disk, as a safeguard against damaging an existing database.

What should we do to fix it:

Check that the ASM disk specification is correct. Otherwise, when storage from a defunct database is reused as part of an ASM diskgroup, specify the FORCE option to the ASM SQL command.