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You can minimize these storm workloads through operational best practices, such as staggering updates to
different virtual machines. You can also test various log-off policies during a pilot phase to determine whether
suspending or powering off virtual machines when users log off causes an I/O storm. By storing
View Composer replicas on separate, high-performance datastores, you can speed up intensive, concurrent
read operations to contend with I/O storm loads.
In addition to determining best practices, VMware recommends that you provide bandwidth of 1Gbps per 100
virtual machines, even though average bandwidth might be 10 times less than that. Such conservative planning
guarantees sufficient storage connectivity for peak loads.
Network Bandwidth Considerations
For display traffic, many elements can affect network bandwidth, such as protocol used, monitor resolution
and configuration, and the amount of multimedia content in the workload. Concurrent launches of streamed
applications can also cause usage spikes.
Because the effects of these issues can vary widely, many companies monitor bandwidth consumption as part
of a pilot project. As a starting point for a pilot, plan for 150 to 200Kbps of capacity for a typical knowledge
worker.
With the PCoIP display protocol, if you have an enterprise LAN with 100Mb or a 1Gb switched network, your
end users can expect excellent performance under the following conditions:
Two monitors (1920x1080)
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Heavy use of Microsoft Office applications
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Heavy use of Flash-embedded Web browsing
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Frequent use of multimedia with limited use of full screen mode
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Frequent use of USB-based peripherals
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Network-based printing
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This information was excerpted from the information guide called PCoIP Display Protocol: Information and
Scenario-Based Network Sizing Guide.
WAN Support and PCoIP
For wide-area networks (WANs), you must consider bandwidth constraints and latency issues. The PCoIP
display protocol provided by VMware adapts to varying latency and bandwidth conditions.
If you use the RDP display protocol, you must have a WAN optimization product to accelerate applications
for users in branch offices or small offices. With PCoIP, many WAN optimization techniques are built into the
base protocol.
WAN optimization is valuable for TCP-based protocols such as RDP because these protocols require many
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handshakes between client and server. The latency of these handshakes can be quite large. WAN
accelerators spoof replies to handshakes so that the latency of the network is hidden from the protocol.
Because PCoIP is UDP-based, this form of WAN acceleration is unnecessary.
WAN accelerators also compress network traffic between client and server, but this compression is usually
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limited to 2:1 compression ratios. PCoIP is able to provide compression ratios of up to 100:1 for images
and audio.
VMware, Inc.
Chapter 4 Architecture Design Elements and Planning Guidelines
45
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