Hi all,
I work at an educational institution. We plan to create a render farm. I'm to research how many nodes of our cluster we would have to use. Are there any statistics how much time takes rendering of one frame?
I know the answer is: it depends. I just need some examples. Maybe there are some information how long Sintel or Big Buck Bunny was rendered?

Thanks in advance for your help.

It depends...

Seriously though your asking a question without giving any details.
It could take blender 5 minutes to render a frame, it could take it a day. It depends on what your rendering and how complicated your scene is. It's pretty easy to do things wrong and make it take longer than it really needs to...

If your doing student projects then your scenes will probably be less complicated than a scene from big buck bunny, so that would probably be overkill.

http://www.bigbuckbunny.org/index.php/our-renderfarm-and-how-it-works/
has some answers to questions you were asking.

You only need 1 machine to render an animation. The more you have the faster it will go, but at the same time how long will those machines just be sitting idle? It's a balancing act, with no wrong or right answer.

I would start small, plan on scaling up but wait to get a feel for what you really need before jumping in too big.

Thank you for your reply and the link.
I totally agree with you. I told my colleagues the same and I think we will do it step by step as you wrote.