Real-Time Media and Virtualization

It is the hypervisor that shares the physical resources between the virtual servers; if the virtual servers are processing non-time-sensitive data, for example, serving a webpage or forwarding an email, a slight delay in processing might not matter. Lync Server deals with real-time audio and video, and the fact that it is real-time is key. Without consistent performance from the server, audio or video could glitch or freeze. Therefore, a virtual Lync 2013 server must perform consistently.

In Lync Server 2013 the load on the servers increases over Lync Server 2010:

• Gallery View now displays video of multiple conference participants simultaneously which impacts processing and network I/O.

• The presence database has moved to the Front End Servers and is replicated between Front End Servers, impacting storage I/O and memory utilization.

The physical hardware recommendations laid out by Microsoft give us an indication of the processing, memory, storage, and network performance required to deliver good Lync Server 2013 performance. Their hardware recommendations are scaled for 6,600 users per Lync 2013 Front End Server based on their user model data. It is important to understand that virtualization is not going to magically reduce this processing, memory, and storage requirement. In fact, virtualization is actually adding overhead in comparison to deploying directly onto physical hardware. This overhead is estimated at around 10% of performance, assuming that all hardware is specified as per a physical deployment.

There are good reasons for virtualizing Lync Server 2013:

• It deploys the Lync deployment onto the existing virtual host infrastructure (often reducing deployment time).

• It complies with a strategy of virtualizing all servers, allowing for consistent management and support.

• It enables the Lync deployment to be easily migrated to a different physical infrastructure in the future (offline migration).

• It can allow virtualization-level backup options.

• It reduces the number of physical servers, and associated heat, power, and space costs.

Reducing the amount of hardware required or costs is not a primary goal of virtualizing Lync Server 2013.