Architecture Planning

A good starting point is to allocate 1GB for 32-bit Windows 7 or later desktops and 2GB for 64-bit
Windows 7 or later desktops. If you want to use one of the hardware accelerated graphics features for 3D
workloads, VMware recommends 2 virtual CPUs and 4GB of RAM. During a pilot, monitor the performance
and disk space used with various types of workers and make adjustments until you find the optimal setting
for each pool of workers.
Estimating CPU Requirements for Virtual Machine Desktops
When estimating CPU, you must gather information about the average CPU utilization for various types of
workers in your enterprise.
CPU requirements vary by worker type. During your pilot phase, use a performance monitoring tool, such
as Perfmon in the virtual machine, esxtop in ESXi, or vCenter Server performance monitoring tools, to
understand both the average and peak CPU use levels for these groups of workers. Also use the following
guidelines:
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Software developers or other power uses with high-performance needs might have much higher CPU
requirements than knowledge workers and task workers. Dual virtual CPUs are recommended for
compute-intensive tasks, if you need to play 720p video using the PCoIP display protocol, and for 64-bit
Windows 7 and later desktops.
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Single virtual CPUs are generally recommended for other cases.
Because many virtual machines run on one server, CPU can spike if agents such as antivirus agents all check
for updates at exactly the same time. Determine which agents and how many agents could cause
performance issues and adopt a strategy for addressing these issues. For example, the following strategies
might be helpful in your enterprise:
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Use View Composer to update images rather than having software management agents download
software updates to each individual virtual desktop.
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Schedule antivirus and software updates to run at nonpeak hours, when few users are likely to be
logged in.
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Stagger or randomize when updates occur.
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Use an antivirus product that is compatible with the VMware vShield API. For example, this API has
been integrated into VMware vCloud
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Networking and Security 5.1 and later.
As an informal initial sizing approach, to start, assume that each virtual machine requires 1/8 to 1/10 of a
CPU core as the minimum guaranteed compute power. That is, plan a pilot that uses 8 to 10 virtual
machines per core. For example, if you assume 8 virtual machines per core and have a 2-socket 8-core ESXi
host, you can host 128 virtual machines on the server during the pilot. Monitor the overall CPU usage on the
host during this period and ensure that it rarely exceeds a safety margin such as 80 percent to give enough
headroom for spikes.
Choosing the Appropriate System Disk Size
When allocating disk space, provide only enough space for the operating system, applications, and
additional content that users might install or generate. Usually this amount is smaller than the size of the
disk that is included on a physical PC.
Because datacenter disk space usually costs more per gigabyte than desktop or laptop disk space in a
traditional PC deployment, optimize the operating system image size. The following suggestions might help
optimize image size:
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Remove unnecessary files. For example, reduce the quotas on temporary Internet files.
Chapter 4 Architecture Design Elements and Planning Guidelines for Remote Desktop Deployments
VMware, Inc. 45