ORA-00304: requested INSTANCE_NUMBER is busy

While starting one of the cluster instance we encountered following error:

SQL> startup nomount pfile='initPROD2.ora'
ORA-32006: BACKGROUND_DUMP_DEST initialization parameter has been deprecated
ORA-00304: requested INSTANCE_NUMBER is busy
SQL> exit
Disconnected

Here we are trying to start instance on node2 and getting this error message, the error message is very clear that the instacne number which we are trying to mount is not available and is already mounted on other instance.

SQL> set pages 300 lines 300

SQL> select inst_id, instance_number, instance_name, host_name, status from gv$instance;



   INST_ID INSTANCE_NUMBER INSTANCE_NAME    HOST_NAME                                                        STATUS

---------- --------------- ---------------- ---------------------------------------------------------------- ------------

         1               1 PROD1            EBSDB1                                                          OPEN

So we should ensure proper instance number are used in parameter files before startup database.