Fail-over to secodary delegated authentication LDAP directory

Crowd has two delegated authentication LDAP directories configured. These are copies of each other and have the same user data and credentials.
JIRA is configured to use Crowd for authentication and authorisation. Crowd defines both directories to be used for authentication for JIRA.
Shutting down the primary directory stops also JIRA authentication. Crowd should be enhanced to support fail-over to the secondary directory.
This enables users easily to use Crowd for improving availablity of authentication with several instances of the same authentication data.