Setting a global limit on sessions

You can limit the number of sessions that a particular server supports, or choose to leave the sessions unrestricted.

When a user subscribes to be notified of another user's status changes, a presence session object is created. Whenever two users start a new chat, an instance messaging session object is created. These session objects take up considerable space in memory. To avoid a scenario in which a very high level of user activity might cause an out-of-memory error to occur, set the maximum session property to a predefined limit that you know is supported. In the event of these limits being reached, the server does not create any new sessions, but does continue to serve existing sessions.

In a cluster, the maximum number of sessions is applied to each node, so the true maximum is the number of nodes multiplied by the maximum sessions value; for example, if your cluster has two nodes and your maximum sessions is set to 5000, then your cluster actually supports a maximum of 2 * 5000 = 10,000 sessions.

There are two configuration levels regarding the maximum sessions limit in Sametime® Gateway: global limits and community limits. For information about the community limits, see the topic Setting a community-level limit on sessions in Sametime Gateway.

The procedure that follows sets a global limit for the maximum number of sessions allowed at one time on a particular server. The global limit that you specify here is enforced on all communities in your IBM Sametime Gateway deployment as a whole, therefore, the sum of all the external communities sessions cannot exceed the global limit.