[AG-TECH] Single vs multiple machine node?

[Christoph Willing]

On 25/03/2008, at 6:49 AM, Dioselin Gonzalez wrote:

> Hello (and greetings to all the people with whom I have worked in  
> the past!!),
>
> In building our nodes I wanted to ask the community your
> thoughts/suggestions/experiences on having a single machine node.  We
> wonder if having a quad-core machine (instead of 3 separate audio,
> video and display ones) will be enough for sessions with many
> attendees, streaming MPEG4 and running shared applications.  Jason
> Bell reported CPU usage of 40% with 4 video streams
> (http://www-unix.mcs.anl.gov/web-mail-archive/lists/ag-tech/2008/03/ 
> msg00045.html);
> we are planning to send up to 8 video streams.


You'll certainly need a newer machine to run so many streams - we've  
recently been using the Dell T3400 quad-core machines and they're  
working very well so far (although not with 8 streams). I believe the  
T3400 is the machine that Jason was also testing with. A good feature  
of these machines is their dual PCIe graphics slots, enabling 2 high  
performance dual output graphics cards to be used.

As for the number of machines, three are almost definitely not  
needed. In particular the separate audio machine is not necessary and  
complicates day to day operation. We always recommend running the  
audio on the display machine - thats the machine the operator is  
mostly dealing with to manipulate the video display streams so its  
the better place to have the audio control too; then there's no need  
to switch between machines. We generally recommend a separate video  
capture machine for anything other than personal desktop nodes.  
There's is usually only 1 or 2 video streams being captured in  
personal nodes. However in the bigger nodes, the proliferation of vic  
instances (1 for each capture stream) can be extremely confusing for  
the operator. Its better keep the multiple vic instances "hidden" in  
a separate capture machine, leaving just a single  
VideoConsumerService (and the AudioService) to run on the display  
machine.

In summary, it may be technically possible to use a single good  
enough machine for everything but its operationally more advisable to  
use a display machine (which also handles the audio) along with a  
separate video capture machine.


chris


Christoph Willing                       +61 7 3365 8350
QCIF Access Grid Manager
University of Queensland