In this post, you’ll learn more about the Oracle ErrorORA-15029: disk ‘string’ is already mounted by this instance with the details on why you receive this error and the possible solution to fix it.
Oracle Error Description
ORA-15029: disk ‘string’ is already mounted by this instance
Reason for the Error ORA-15029: disk ‘string’ is already mounted by this instance
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.
How to fix the Error ORA-15029: disk ‘string’ is already mounted by this instance ?
You can fix this error in Oracle by following the below steps
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.