VRay RT DR

[padre.ayuso]

I have a problem when I try to DR another machine using RT. I turn on the RT Server on the slave machine and I connect and they seem to find each other, but no go, it just hangs. Turn DR off and it works just fine. To note, the slave machine and the workstation I'm on have different CPU RAM amounts. I have turned off firewalls et al., but I don't know what else to do. Is there something I'm not doing right? Is the difference in CPU RAM an issue? Both machines have the same Graphics Cards, exact ones, all were bought together from the same company at the same time.

Alex

[savage309]

The amount of RAM does not matter. Are you trying RT GPU or RT CPU ?

[padre.ayuso]

RT GPU. Do you have a write up of the steps that I'd need to go through to turn this DR on? I have only done them based on intuition. I have been able to successfully DR on RT GPU mode before.

[savage309]

There are docs files for DR - http://docs.chaosgroup.com/plugins/s.../view/10390211

Because of the OS on some setups the GPUs can not be seen by applications (like V-Ray) if there is no monitor attached to the computer. The same goes with Remote Desktop - it happens to not be able use GPUs sometimes as well. Can you check the log on the DR machine to be sure it sees the GPUs ? Alternatively, you can use a tool named ocldeviceselect for that - it is shipped with every V-Ray installation and tells you what GPUs are available on the machine.

[padre.ayuso]

Hi there
Thank you for that. OK, so I'll be doing some tests with some very simple scenes, and see how it goes. I'll try different options here and there and see how it goes and hope to be able to nail down what is happening. To answer some of your points, the DR machine I'm trying to "Juice" for lack of a better slang, is a workstation that is connected to two monitors, right across from where I seat, so that would not be a problem. When I have sent the jobs, the machine I sent the job from, my workstation, says that it has recognized the DR machine, however DR machine is not registering or doing anything, just sits there, waiting for me to crack a joke or something. So the DR machine and I seat at an impass and the rendering does not start. I stop the whole thing, turn off DR and re-send the render on my machine, with only my GPUs turned on, and voila, all of a sudden it works beautiful. I was using 3.03.03. However, I have just installed 3.03.04 yesterday and I'll be doing some tests on this today/tomorrow and hope to be able to crack this and give some input in case others have run into this problem and have not been able to solve it. I could not find the ocldeviceselect.... sorry. Where could I find this?

Thanks for your help and assistance.
Best
alex

[padre.ayuso]

OK, so updated news. So far I was able to DR successfully on a very small scene. Then I went onto a more complicated scene and at one point I thought something went wrong and crashed, but here is the confusing part, and maybe this is where some interaction between VRay and user may help (hint). On the DR machine, I was checking the CPU and all along it was displaying 100% usage while my GPU usage spiked to 100% every now and again. Meantime I had no image on my workstation, no feedback. Then I remembered, LC had to be calculated by both machines first and perhaps VRay was not displaying and this seems to be a true datum. Because when the DR machine finished processing the data through the CPU, my image started appearing on the workstation and the GPU spiked to 100% on the DR machine. SO that solves my mystery. Now, I think if the interaction can be tweaked so the user knows what is happening, then I or whomever is using DR on RT GPU, won't freak out.

Best
alex

[savage309]

Good to know it worked, thanks for the pointer.

[padre.ayuso]

Alright, one other question, I sent to render last night a test scene. two GTX 970 on my workstation and another two GTX 970 on another workstation on the network. All maps on the network accessible to both machines. Resolution 3000x2850. Noise level at .005. Time laps, 1 hour and 51 minutes.

Today I sent the same scene, nothing changed, turned off all cards bar one on my computer. 1 Hour and 51 minutes. Any pointers as to why it would take longer? Shouldn't 4 cards take 4 times less than 1 card? Confused...

[savage309]

Using 4 GPUs should make the render ~4 times faster, yes. So something is not right, but what exactly is hard to say what without more information.
What is the exact setup (how many GPUs in how many machines) ? Can you monitor the GPU usage to see if the GPUs are being used at all (are you sure they are enabled for RT GPU rendering) ? What are Ray Bundle Size / Rays Per Pixel values (having them too low for production is not suggested) ?