Guidelines for M-series and L-series Host Scaling

Scope

One of the principal advantages of deploying multiple users on a single host–be it a PC, physical server or virtual machine–is that you can readily scale the size of your deployment as your users’ needs grow. Rather than being forced to purchase expensive new computing resources for each new user, you can simply expand the capacity of your host system.  vSpace Server 6 now allows you to extend the number of users per server up to 100 users depending on your user workload, host system performance, and client devices being used.

The number of users, intended application suite and overall performance expectation determine how powerful a host system must be in order to deliver the desired end-user experience. This document provides high-level guidelines for determining the system requirements for various numbers of L-series and M-series users with various computing workloads. This document can be used as a starting point for sizing your deployment – but your own in-house testing should be used for the final determination of your host systems’ configurations.

Understanding Use Cases for General Usage and Video Playback Workloads

Prior to deploying vSpace, you should develop use cases for the users you expect to connect to a host. An important consideration in developing use cases involves determining the number and types of applications users will need to operate. These requirements help you identify and measure the users’ standard workloads. For example, you should measure the CPU, memory and storage utilization for a typical user workload in your environment. This workload data and the total expected number of users will help you determine the system requirements for your host system.

An important concept to keep in mind is the difference in resource usage seen when comparing ordinary office application usage and multimedia streaming. As demonstrated in the chart below, our Core i7 test system was able to support roughly 60 users whose workload was comprised entirely of common office application usage. Once the use-case switched to video streaming however, the number of users that could be adequately supported by the same hardware specs dropped to 20. This is a good example of how demanding video streaming and other similar tasks (such as browsing flash intensive websites) can be on a system. With regards to video streaming, another defining variable is the size of the video being streamed. For example, 720p video contains approximately three times (3x) the amount of pixel data as 480p video. Understandably that translates to a notable difference in resource requirements between the two formats.

For the purpose of our testing, workloads were divided into three typical usage scenarios each of which involved sequentially cycling through and completing tasks within the listed applications. These workload profiles have been detailed below. We've also included test data for two different levels of video fidelity which represent "extreme" usage scenarios wherein all users present were streaming videos. Naturally, you are not required to build your host specifications around extensive high definition video streaming unless that is a core requirement for your deployment. 

Low Workload Scenario

• Microsoft Office® applications: one instance of Word and Excel® per user
• Adobe® Reader 10 — opening and viewing a PDF file
• Internet Explorer®, with two windows/tabs active

Medium Workload Scenario

• Microsoft Office applications: one instance of Word, Excel and PowerPoint® per user
• Adobe Reader 10 — opening and viewing a PDF file
• Internet Explorer, with three windows/tabs active

High Workload Scenario

• Microsoft Office applications: one instance of Word, Excel and PowerPoint per user
• Adobe Reader 10 — opening and viewing a PDF file
• Internet Explorer, with four windows/tabs active
• Video file (played in Windows Media Player) in a half-screen size window at 480p resolution

480p Video Stream (all users)

• Media Player Used: VLC Media Player
• Video used: "Beauty of Pixar" (480p, 24 fps, 24bit color)*

720p Video Stream (all users)

• Media Player Used: VLC Media Player
• Video used: "Beauty of Pixar" (720p, 24 fps, 24bit color)*

*Hardware Video Scaling by NumoTM

NComputing's M300 and L300 series terminals feature the Numo chip, which allows for real-time hardware video scaling at no additional resource cost to the host. This means that users are free to resize video playback freely to cover any percentage of the screen including full screen playback without placing any additional burden on the host system or network. 

 Typical Maximum Number of  Users by Workload/Host Configuration

Conclusion

The above guidelines represent estimates of required system configurations that are generally expected to result in a satisfactory user experience for the workloads as defined. The number of users that your installation will support depends upon the host's configuration, the cumulative resource demands of applications being run, and your end-users’ performance expectations. Performance results are highly dependent upon the individual host hardware, memory, applications being used, operating system and network conditions within any LAN. Host requirements will vary, please test your multi-user environment before deployment.

For deployments focusing on video playback: remember that in addition to host hardware specifications, performance is affected by the encoding used on the video itself and the software being used to play the video. Keep in mind that not all media players are created equal. Streamlined applications like VLC media player will frequently use fewer system resources during playback than the stock media players often included with new computers. Testing should be performed to find the right playback software for your deployment

For large vSpace deployments you also need to consider other factors that affect the user experience, including network bandwidth, whether or not virtual machines/hypervisors are used and host capacity and performance, including the number of available IOPS, and available host memory and server cores.

For information about additional system configuration requirements, deployment guidelines and system tuning, please see the “NComputing L-Series Deployment Checklist” in the NComputing Knowledge Base (www.ncomputing.com/kb/).