Planning for Virtualization
Many modern datacenters are moving toward virtualizing their workload as much as possible. Lync Server 2010 supports virtualizing all its roles, although it is supported with a lower-rated capacity when virtualization is involved. This isn’t to suggest that virtualization adds overhead, but should be taken as a statement from Microsoft that although it supports Lync Server 2010 on virtualized systems, it would rather see them run on physical hardware and, as such, lower their capacity ratings for virtualized roles. Microsoft even goes as far as to state that if the virtual host is given dedicated resources equivalent to a physical host, it will support the same number of users as the physical host. Its conservative stance is based on the resources that are typically allocated to a given virtual guest.
For example, when using virtualized servers, Microsoft suggests a maximum load of 2,000 users per virtual Standard Edition server and a maximum of 5,000 users per virtual Enterprise Edition Front End Server. Compare these values to the 5,000 users per Standard Edition and 10,000 per Enterprise Front End Server when used with physical hardware.
Note
Microsoft officially supports only Windows Server 2008 R2 for the guest operating systems when used for Lync Server 2010. On the host side, both VMWare and Hyper-V virtualization platforms are supported.
Given that typically virtualized environments are shared across a variety of applications and usually connected to some form of shared storage, pay careful attention to the amount of disk I/O available to various Lync Server 2010 roles.
Caution
Don’t automatically assume that because a virtualization environment is attached to a high performance SAN that there’s automatically enough I/O to keep a new application happy. Always evaluate current loads on the infrastructure, both the virtualization farm and the back end storage, to ensure that the new loads imposed on the environment won’t degrade the performance of all applications running on the farm.
Another area to plan for is the networking aspect of the virtualization platform. To optimize performance for Lync Server 2010, it is recommended that each virtualized host be bound to a dedicated Ethernet port on the host system. For large deployments, this can mean a large number of Ethernet ports. Strongly consider deploying multiport network interface cards (NICs) into virtualization hosts.
Another technology to consider, especially when virtualizing Lync Server 2010, is the use of NICs that support Virtual Machine Queue (VMQ). VMQ is a virtualization technology that allows for the efficient transfer of network traffic to a virtualized operating system. VMQ enables virtual machines to filter their queue of packets within the NIC to improve the efficiency of network traffic. If the NICs support it, VMQ can be enabled for individual virtual machines from within the hypervisor’s management console.
It is also recommended to increase the transmit and receive buffers on NICs dedicated to virtual machines to at least 1,024 to avoid packet loss. Not all NICs support a buffer of this size, so take this into account when planning where to deploy the virtual machines for Lync Server 2010 or when planning what hardware to purchase to support a virtualized Lync Server 2010 deployment.
→ For more detailed information on how virtualization works with Lync Server 2010, refer to Chapter 25, “Virtualization.”