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Table Of Contents
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 or Quad virtual CPUs are recommended
for 64-bit Windows 7 virtual machines running compute-intensive tasks such as using CAD
applications, playing HD videos, or driving 4K display resolutions.
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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 instant clones or View Composer linked clones 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.
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Turn off Windows services such as the indexer service, the defragmenter service, and restore points. For
details, see the topics "Optimize Windows Guest Operating System Performance," "Optimize Windows
7 and Windows 8 Guest Operating System Performance," and "Overview of Windows 7 and Windows 8
Services and Tasks That Cause Linked-Clone Growth," in Setting Up Desktop and Application Pools in
View.
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Choose a virtual disk size that is sufficient to allow for future growth, but is not unrealistically large.
Chapter 4 Architecture Design Elements and Planning Guidelines for Remote Desktop Deployments
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