ORA-00304: requested INSTANCE_NUMBER is busy

Oracle Database - Enterprise Edition - Version 11.2.0.2 and later
Information in this document applies to any platform.
***Checked for relevance on 21-Jul-2017***

SYMPTOMS

Unable to create a single instance "DUPDB" with a database name "UTLD" on a Exadata Server, when there are already exists a two node RAC database having Database Name "UTLD" on the Exadata servers. 

• Exadata box with four servers: DB01, DB02, DB03 and DB04.

• A two node RAC database "UTLD" exists on DB01 and DB02.

• When attempting to create a single instance "DUPDB" with a database name of "UTLD" on DB03; it fails with:

$ echo $ORACLE_SID
dupdb

SQL> STARTUP NOMOUNT PFILE='/u02/oradba/initdupdb.ora'
ORA-00304: requested INSTANCE_NUMBER is busy

• Pfile(initdupdb.ora) has:

instance_name='dupdb'

db_name='utld'

CAUSE

 
As the database  UTLD exists in two nodes , Oracle believes you want to add the instance in the other node.

SOLUTION

 Add the parameter db_unique_name with a unique name in the init<SID>.ora file.

Eg: 

db_unique_name = dupdp

ORA-00304: requested INSTANCE_NUMBER is busy

原文：http://blog.51cto.com/roidba/2114433