Whenever information about the Oracle instance changes, such as the instance user name and password, you must update the Remote Agent Utility.
When Oracle RAC nodes are added or removed, you must enter information about any changes to instances in the Remote Agent Utility. After these changes are entered, the Backup Exec media server discovers them.
If the changes are not updated in the Remote Agent Utility, the error “Unable to attach to a resource…” may appear when you run a backup job.
More Information
Configuring the Oracle Agent on Windows computers and Linux servers