Mail is a critical corporate application, and users and administrators expect 24×7 mail availability. With IBM Lotus Notes® and Lotus Domino, high availability is achieved with Lotus Domino clustering and mail file replicas. The Lotus Notes client contains explicit code to cope with scenarios in which a Lotus Domino server with which it is communicating is no longer available.
After a slight delay (as it awaits an attempted connection or communication to complete), the Lotus Notes client notifies the user that the server is no longer available and asks the user to confirm that it is to switch to another known replica server.
With Lotus iNotes, however, high availability requires the assistance of some additional infrastructure, such as an Application Delivery Controller (ADC). ADCs offer many benefits in the data center, including these:
* Improving application reliability (through application monitoring and load balancing)
* Enhancing security (application firewalls) and acceleration (TCP and HTTP optimizations)
* Off-loading servers from some of the more compute-intensive tasks; for example, Secure Sockets Layer (SSL) encryption
