NComputing VSPACE U170 Manual de usuario
NComputing is a registered trademark. Other trademarks and trade names are the property of their respective owners. Copyright 2010.
Configuring a U170 Shared Computing Environment
NComputing Inc.
March 09 2010
Overview
NComputing's desktop virtualization technology enables significantly lower computing costs by
letting multiple users share a single PC. With the U170 product up to 10 users can share and
simultaneously access a single PC.
The concept of shared computing is not new in fact if you go back to the early days of
mainframe computing multiple users shared a single system using basic access terminals. PCs
forever changed the economics of computing – allowing people to have the power of the
mainframe on their desk. As technology has progressed the PC has become so powerful that
most users are now only using a fraction of the capability of the machine resulting in wasted
resources and wasted power.
NComputing takes this excess power and shares it among multiple users resulting in more
efficient usage of resources and hence lower costs easier set-up and management and a far
superior environmental footprint.
NComputing manages the shared PC resources with the vSpace™ desktop virtualization
software and distributes those resources to each access device. NComputing vSpace software
efficiently accesses the features and functions inherent in the host PC’s operating system to
distribute its capabilities among users with minimal overhead. Therefore every U170 station can
see operating system responsiveness and application performance that is nearly the same or equal
to that of the host PC.
Setting up a multi user environment is straight forward but there are a few fundamental
computing attributes that should be known and understood. The document will outline how to
best configure a U-series environment by discussing the best configurations and topologies for 5
and 10 multi-user environments.
NComputing is a registered trademark. Other trademarks and trade names are the property of their respective owners. Copyright 2010.
Determining Your U170 Environment
There are a number of attributes in choosing the right configuration and topology for a U170
deployment; we will cover each of the following:
- Topology
- Host PC
- Power: Powered hubs and cables
- Host or system performance
o CPU
o Memory
o USB bus
- Application performance
- Internet performance
It is important to note that all of these attributes are interrelated and what is implemented on one
attribute may affect performance on another so understanding these computing fundamentals is
important.
It is important to read the Users Guide first; this document will not address install processes or
procedures.
The topology or layout of a U170 environment is very important as USB compliance power and
cabling/hub needs must be met. Please map out your topology in advance to make sure you
understand what it will look like in advance performance and power considerations (noted
below) and what cables and hubs will be needed. We will provide a topology check list after we
discuss the factors that can impact the topology and performance.
Host PC
The recommended host configuration is defined in the User Guide; please make sure to choose a
host with enough CPU power (for video) memory for the number of users and multiple USB 2.0
buses (if needed). Remember to configure the host so that USB ports are not shut down as this
will terminate any U170 active session.
Power: Powered Hu s and Ca les
The USB 2.0 specification calls for 500 mA per port. Each USB device with a standard mouse
and keyboard attached is expected to use about 400 mA of power (this includes a power
allowance for the mouse and keyboard is up to 150 mA). Therefore there can be only one U170
per USB port.
Use POWERED hubs when daisy chaining U170’s or when adding any additional USB devices
downstream to a U170. The USB specification and all OS’s allow only 5 hops on a port so
don’t exceed this number.
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Cable quality is IMPORTANT! Use only high-quality USB 2.0 compliant (not compatible)
cables. We recommend a minimum size of 24 awg (power) and 28 awg (signal). Cheap cables
can cause excessive voltage drops that can lead to system stability issues.
The maximum length of a USB 2.0 compliant cable is 5 meters. A hub or repeater can be used to
extend the cable to 10 or even 15 meters but each hub (the U170 is a hub) or repeater counts as a
hop and you can’t exceed 5 hops on a port.
CPU Performance:
It is easy to check CPU utilization by using the Windows Task Manager in Windows. It gives
clear and constant feedback on the percentage of processing power consumed making it easy to
evaluate your environment to determine if the amount of processing power needed for a given set
of applications is available. For the majority of productivity applications and many multi-media
applications most dual core processors provide more than enough performance to handle 6 or
even 10 users at one time*. NComputing recommends you test your actual application set
prior to wider deployments.
NComputing’s operating system testing with our vSpace software has demonstrated excellent
“fair share” processor utilization that enables all tasks to be serviced equally. This means that
even if the CPU usage spikes to 100% vSpace and the operating system evenly distribute the
available CPU capacity across all the stations. So in the cases where the CPU hits 100% each
individual station’s performance slows on a sliding scale. For example a user’s perceived
performance may move from 2.5 GHz to 2.0 GHz to 1.5 GHz and then spring back once the
demanding task is completed. Additionally those times when the actual processing requests
exceed what was anticipated are usually very brief and user performance normally returns to
near the host PC’s native speed very quickly.
* Generally the most stressful CPU test for a U170 is video decoding at full screen. Playing a
video stream is highly dependent upon the video file type; then somewhat on the video player
(decoder) and screen resolution. We benchmark against D1 (or DVD) sized videos of up to a
NTSC Wide-screen resolution of 720x480. Again most current P5 class Intel/AMD dual core
processors can handle many streams at once if more are needed simply upgrade the processor.
Memory:
The second PC resource to check is memory utilization and it can easily be checked via the same
performance tab within the Windows Task Manager. NComputing generally recommends
provisioning the host PC with 2-4 GBytes of memory.
Also check your paged memory usage to be sure it doesn’t exceed the OS limits of 372 MB (XP)
or 530 MB (Server 2003) (marked in red in the Task Manager below).
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USB Bus:
The U170 device connects to a PC through any USB 2.0 compliant connection method directly
through a USB cable included in the kit or a powered USB 2.0 hub. Modern computers normally
provide 480Mbps or 960Mbps USB bandwidth depending on whether they have one or two USB
buses. The table below describes the maximum bandwidth of the USB bus for modern PC
motherboards. PCs that contain multiple EHCI controllers will have better video performance
when running more U170 devices on a PC.
Vendor Chip Set
USB or EHCI
controllers
Maximum
Bandwidth
AMD SB710 2 120 MB/s
Broadcom HT1100 3 180 MB/s
Intel ICH8 2 120 MB/s
Intel ICH9 2 120 MB/s
Intel ICH10 2 120 MB/s
nVIDIA IO Series 2 120 MB/s
* Note: This is NOT a comphrensive list of chip set that have more than one US B bus.
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Two buses are important if you are running > 4-5 users and you wish to maximize the video
performance. With 4 or more simultaneous video’s playing the USB bus bandwidth is pushed
and it may impact video performance. If this happens the U170 will drop frames from the video.
To find out how many USB buses your PC has simply open Device Manager and view “Devices
by connection”. The number of “Standard Enhanced PCI to USB host Controller” is the number
of USB buses. In the example below the PC has two USB buses.
To take advantage of multiple controllers connect any downstream hubs back to the PC directly
rather than connecting all U170s downstream of one USB connection. Adding an additional USB
controller card through a PCI slot to a PC is also an option. Depending on how many U170
devices attached to the PC and how many USB buses the PC has there are typically no
bottlenecks between the U170 stations and the host. Normal PC network performance rules
apply to the host PC and the most common limit is the connection bandwidth to your Internet
service provider. However this bandwidth is a shared resource for all users whether using
individual PCs or using a shared environment.
NComputing is a registered trademark. Other trademarks and trade names are the property of their respective owners. Copyright 2010.
Application Performance:
When setting up a multi-user environment testing of your applications in a typical usage model
should be conducted to determine that the configured PC’s resources (CPU and memory) are
sufficient to meet performance expectations. Any dual core system from 2008 and beyond should
more than meet the vast majority of application performance needs for most educational or
business users. The following data show how well 10 users can run on a standard PC available in
the market today.
If your testing indicates that a system’s dual core processor does not meet your performance
needs then the option is to improve the resources in the host PC by going to a faster processor or
using one with more processing cores.
Internet Performance:
There is really no difference between running 10 users on a single multi-user PC or running 10
stand alone PC’s. Just make sure to connect the host to the LAN with the proper allowances for
multiple users to your broadband services.
Topology
As mentioned topology of a U170 environment is very important and can be impacted by the
items mention above; therefore we are providing the following topology check list:
Enough CPU power to run your desired number of video streams
Two USB buses if >4-5 users running video simultaneously
Make sure there are no more than 5 hops in the topology
Maximum distance is 5 meters per hop
Extra USB Ports
You will need to add powered USB hubs to add extra USB ports
downstream of the U170 as the U170 automatically assigns most
downstream devices to the U170 session.
Power
There can be no more than one U170 device per USB port (and each
port must support the specified 500mA of power). Use only powered
USB hubs.
Cables Use quality cables
Distance
Using quality cables don't exceed more than 5 hops on a single USB
port
U170 Topolo y Check List
Host
USB Compliance
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The following topologies give valid examples how to count a USB “hop” and how not to exceed
them. We include two other valid topologies later in the document.
This is a daisy chained topology of 5 hops. Note that the power hubs add the ability to hop and
an extra USB port in the first two U170 devices.
This is a topology of only 3 hops. Note that the first power hub add the ability move up to 5
meters from the host and then split out four U170 devices (at up to another 5 meters). And the
second series of powered hubs are optional but shown here add extra USB ports for flash drives
a printer or other USB devices.
#2
#1
#4
#3
#5
#1
#2
#3
NComputing is a registered trademark. Other trademarks and trade names are the property of their respective owners. Copyright 2010.
U170 5-User Environment Example
In our 5-user example configuration we used an off the shelf Lenovo 3000 H Series
1
that sold
for about $300. We connected four U170 devices 5 LCD monitors and Windows Server 2003
Standard Edition as the OS. Many PCs today have eight or more USB ports. There is no need for
a USB hub if there are enough ports available. We connected the four U170 devices directly to
four USB ports in the back as shown in the picture below.
To demonstrate the performance we started a 720x480 video in full screen mode on each U170
devices. Video decoding is a very processor client and USB bus intensive task and therefore a
good test to determine if all these attributes of the host system are working well. Once we
launched the four video streams we monitored CPU and memory usage from the host with
Windows Task Manager. A 720 x 480 video clip typically represents a widescreen DVD quality
image.
NComputing is a registered trademark. Other trademarks and trade names are the property of their respective owners. Copyright 2010.
As shown from Windows Task Manager the CPU usage is about 85% and memory usage is less
than 600MB of memory while all devices are running full screen video at the same time. This
shows that this low cost dual core CPU has no problem handing the four streams and that
memory is NOT taxed in this scenario.
Our topology for this five user environment looked like this:
PC
U170
Port 1 Port 2
U170
Port 1 Port 2
U170
Port 1 Port 2
U170
Port 1 Port 2
NComputing is a registered trademark. Other trademarks and trade names are the property of their respective owners. Copyright 2010.
USB bandwidth utilization is not a feature of the Windows Task Manager so it is not an easy
attribute to measure. The maximum specified bandwidth of USB 2.0 is 480 Mb/sec but in reality
the practical useable bandwidth is about 400 Mb/sec. A typical U170 device runs at about
10Mb/sec at idle and a video stream running between the host PC with vSpace and the U170 will
take up to 130 Mb/sec of bandwidth to support up to 30 frames per second (fps). If the USB
bandwidth does not exist to support 30 fps then the U170/vSpace system will begin to drop
frames in the video to make up for the lack bandwidth. Our testing has shown that about four
full screen videos (depending upon the video format size decoder (player) and USB bus
implementation) can play without a noticeable frames dropping. If your usage pattern is to use a
lot of full screen videos simultaneously then we suggest you implement only up to 4 users per
USB 2.0 bus to ensure better video quality.
Therefore the best set up or topology for nine users is to obtain a host PC with two USB buses
and to divide those buses among the users by having four users on one powered hub and five
users on the second hub. Please refer to the previous table for chip sets with two USB buses or a
USB 2.0 PCI card can be added to the host. A topology that looks like this:
Each U170 kit contains one device that adds a new user to a shared PC. Up to nine U170 devices
may connect to a PC and support ten users (including the host) simultaneously. The U170
combined with a modern PC provides the most affordable and powerful shared computing
environment in the market today.
Otros manuales para VSPACE U170
1
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Otros manuales de Terminal táctil de NComputing
