SQL*Plus can connect to only one instance at a time. There is no way around this limitation. If this limitation were removed, how would your SQL statements know which instance to submit a SQL statement to? In some cases, that question would be impossible to answer.
Other applications may be able to connect to multiple instances at the same time. That is how those applications are designed. SQL*Plus was not designed this way.
Dig Deeper on Oracle database design and architecture
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.