Failover Options on Clients

Incorporating enough intelligence in the clients so that they can failover to alternate Oracle directory servers in case the primary Oracle directory server fails is a good option in some cases. This requires the clients to cache alternate server information and use it upon recognizing connectivity loss. This method of guaranteeing availability is viable only for deployments in which one has full control over the type of clients accessing the directory.

This section contains these topics:

• Alternate Server List from User Input

• Alternate Server List from the Oracle Internet Directory Server

Alternate Server List from User Input

The clients can be designed to take input from the user on the list of alternate Oracle directory servers so that the clients can automatically failover in the event of a failure of the primary server. However, as the number of clients increases, this option would not scale very well in terms of administration of client installations.

Alternate Server List from the Oracle Internet Directory Server

Oracle Internet Directory supports a DSE root attribute called AltServer. This is an LDAP Version 3 standard attribute and is to be maintained by the directory administrator. It points to other Oracle directory servers in the system with the same set of naming contexts as that of the local server. When connectivity to the local server is lost, clients have the option of accessing one of the servers listed in this attribute. This option requires explicit administrative action to maintain this attribute.

Clients should cache the information in the alternate server list for use in the event that the primary server becomes unavailable.

Setting the Alternate Server List by Using Oracle Directory Manager

To set the alternate server list:

1. In the navigator pane, expand Oracle Internet Directory Servers, then select a server instance. System operational attributes appear in the right pane.

2. In the Alternate Server field, enter the name or names of alternate servers.

3. Choose OK.

   See Also: RFC 2251 at http://www.ietf.org for details about the usage of altServer attribute "Managing Attributes by Using Command-Line Tools" for instructions about setting the AltServer attribute