General Sizing

Microsoft provides some general sizing guidelines, which are summarized in Table 26.1.

Table 26.1 General Sizing of Servers

A dual 2.0 GHz, 16 GB supports 10,000 users as a Front End Server, whereas a dual 2.0 GHz, 32 GB supports up to 80,000 users as a Back End Server. That said, it is generally a good idea to account for an n+1 design when populating Front End Servers. If you were to plan for 30,000 users, take that number and divide it by the 10,000 users per Front End Server and add 1 for a total of 4 Front End Servers. This places a normal load of 7,500 users per server with the capability to redistribute to 10,000 users per server should a Front End Server suffer a failure or should it need to be brought down for maintenance.

If a site has fewer than 10,000 users and a typical audio/video conferencing load, it is generally recommended to collocate the A/V Conferencing Server role with the Front End Server role. Sites with a larger number of users should deploy a dedicated A/V Conferencing Server. In general, an A/V Conferencing Server can support around 1,000 concurrent A/V conference users. So, if your users are particularly fond of A/V conferences, you might need to deploy more A/V Conferencing Servers.

For non-voice deployments that support external users, the typical rule of thumb is one Edge Server for every 15,000 remote users. It is recommended to always deploy at least two Edge Servers to provide for redundancy.