Users Guide

Solutions Overview Guide 19
peak, average, and low utilization metrics. The information from this
virtualization assessment effort will assist in sizing the virtual machines. Dell
offers consulting services to assist with these efforts.
For a list of Dell PowerEdge servers that are recommended by Dell for hosting
virtualization workloads, go to www.dell.com/servers.
Processor Considerations
Hyper-V is currently supported on systems with up to 24 logical processors.
With multi-core processors, choosing physical processors depends on many
factors including the type of workload, number of sockets on the Dell
PowerEdge server, CPU utilization goals, and power consumption
requirements.
NOTE: Hyper-V support on systems with larger than 16 logical processors requires
an update to be applied on the system. For more information, refer to KB956710 at
download.microsoft.com.
The number of virtual processors to be assigned to a specific virtual machine
depends on the requirements of the workload that runs on the guest
operating system. Windows Server 2008 Hyper-V allows up to 4 virtual
processors to be assigned to a specific VM (support varies for different guest
operating systems). In Hyper-V, virtual processors in VMs do not have a one-
to-one mapping with the logical processors on the server. The Hyper-V
hypervisor handles the scheduling of virtual processors on any available logical
processors. The general guidance is that when the virtual workload is highly
processor intensive, using multiple virtual processors in a VM might be
effective since more physical processors will be used. Since use of multiple
virtual processors also adds additional overhead, careful planning is required
in determining the virtual processor allocation to VMs.
For more in-depth information, refer to the Performance Tuning Guidelines for
Windows Server 2008 document at http://www.microsoft.com.
As mentioned earlier, Hyper-V has the following requirements for the physical
processors:
• Support for x64 extensions
• Support for DEP
• Support for Virtualization Extensions (Intel VT or AMD V)