Topic Last Modified: 2010-11-10

Microsoft Lync Server 2010 introduces a new feature that enables you to take a server offline (for example, to apply software or hardware upgrades) without any loss of service to users. When you specify the option to prevent new connections or calls to a server in a pool, it stops taking any new connections and calls as soon as you implement this option. These new connections and calls are routed through other servers in the pool. A server that is preventing new connections allows its sessions on existing connections to continue until they naturally end. When all existing sessions have ended, the server is ready to be taken offline.

When you prevent new connections to a Front End Server, some Lync Server 2010 features and services rely on the new DNS load balancing feature to ensure proper that it functions properly. If you are not using DNS load balancing on the pool, connections through these services may not be re-routed to other servers during the period that the server is preventing new connections, and thus when the server is taken offline some sessions and calls may be interrupted. The features that rely on DNS load balancing to ensure that this option operates properly are as follows:

For details about DNS load balancing, see DNS Load Balancing in the Planning documentation.

In addition to preventing new connections for all services on a server running Lync Server 2010, you can also prevent new connections for individual Lync Server services. For example, this method is useful in a situation where you need to apply a Lync Server update that does not require the whole server to be shut down. Note that when you prevent connections for one service, you must select a service as it is grouped and displayed in the Windows list of services. For example, the Lync Server Front-End service and the data collection agent for Monitoring Server are separate Lync Server services, but in the Windows services list they are consolidated and shown as the RTCSrv.exe service. You can prevent new connections for the RTCSrv.exe service, but you cannot prevent new connections for these two individual underlying Lync Server services separately.

When you set a server to prevent new connections, and then restart the server, by default the server will immediately begin accepting new connections after it starts. To prevent this, set the server to only pause and resume manually, before you restart the server.