Oracle Error Message
ORA-15029: disk ‘string’ is already mounted by this instance
Reason for the Error
An attempt was made to add to a diskgroup a disk that was already mounted by the current instance as part of some (possibly other) diskgroup.
Solution
Specify a different disk in the command. Note that not even the FORCE option can be used to correct the situation until the diskgroup containing the disk becomes dismounted by this instance.
