Recommended Simulation hardware

[Svetlin.Nikolov]

Hey all,

The topic is raised pretty often, so here is what we know about fast and slow simulation hardware:
https://docs.chaosgroup.com/display/...sterSimulating

Cheers!

[TomGore]

I have a question regarding hardware: With my i7-3930, 64 gigs of RAM and some about 30TB total disk space i can handle no more than 200.000.000 grids and it gets very heavy/slow/huge cache files, almost all ram used, on the verge of crash. Vray render times - about 2 hours per frame because of volumetric geometry mode. I've heard about you folks going more than 1.000.000.000.000 voxel grids. How this is possible and what particular hardware allowed you for such sims? (cpu, ram, hdd). I am planning some rig update and I'd love to hear from people who actually tested/worked in Phoenix ultra-huge scenes. What were your sim times for such a huge grids? Exactly what kind of single pc handled the scene? With volumetric business it is hard to divide sim into several machines, so the sim one has to be a powerful rig. I'd buy the system exactly like the one allowed you for work with 1 billion voxels sims...

[Svetlin.Nikolov]

Hey,

Keep in mind that each voxel can hold a different amount of data - smoke is 4 bytes, fuel is 4 bytes, but velocity is 12 bytes and RGB is 12 bytes as well. During simulation of fire/smoke the channels are duplicated. Sim times are doubled when using twice more steps per frame and are also hugely affected by the conservation quality as well. I assume you mean fire/smoke sims here.

Rendering times do depend on the cache size of course, but there are both Phoenix and V-Ray render settings which can degrade or improve performance by magnitudes, so it's very important to share those as well.

Cheers!

[TomGore]

Of course, I was reffering to typical production scenario with most used channels. But the question was: what was the heaviest sim you ever performed and what hardware specs do you use at Chaos to run such test sims?

[Svetlin.Nikolov]

Yup, this is why I was referring to the RGB channel - since some setups don't require it, you'd get roughly 40% higher upper limit With 64 gigs off the top of my head I had sims about about 300M running. The people that I know of, reaching over a billion, were doing liquid sims where you don't need so many grid channels, on machines with more than 64 gigs.

[TomGore]

And which channels take the most of our hard drives?

[Svetlin.Nikolov]

RAM usage is as above, and cache usage is roughly proportional, but since the caches are compressed by default, some channel compress much better than others - e.g. RGB is compressed better than velocity.

[squintnic]

wemt to see if this has been updated but it seems to be missing or i cant log in with my chaos account? used to be not pass protected?

[georgi.zhekov]

Ah, just the link broke. Here is the correct one - https://docs.chaosgroup.com/display/...sterSimulating

We will update the top one a bit later as well.

Cheers!