Baking of several particle systems I am doing this tutorial. have two particle systems in my scene (for the same object). One particle system is for generating shards of glass and the other one for smoke &amp; fire. I should say that I should do two bakes, one for each particle system. Is that right ? 

I think I am a bit confused about the "baking" options. 

A) Particle System "Shards of Glass". As I said I have one particle system for generating shards of glass. The particle system uses "shards of glass" objects. In the "particle system" box there is an option to bake. This is to bake the emission of shards of glass ? 

B) Smoke and Fire Simulation. A cube is used for the "domain" and a  particle system for the "flow" of smoke and fire. When dealing with smoke and fire in tutorials the baking is done in the domain (but why not in the particle system)? Why is that ? Why is the baking not done in the particle system (the particle system emits the smoke) ?

I guess I have a basic non-understanding about all these baking options.
First off, particle systems are responsible for emitting particles, they have nothing to do with any smoke or fire simulations; on the other hand, smoke simulation is used for emitting smoke, not for particles. Particle system can be used as emitter for smoke (instead of actual mesh), - but their data is different and you can't bake smoke simulation from particle system panel (unless baking everything, see below).  

Hence there is Bake button for baking in their options. It will work per each physics simulation - each smoke / fire sim will be baked from its domain, particle systems - from their options per each particle system, same for dynamic paint etc. With this way you'll bake them one by one.



The only way which is independant on these options is to bake all physics at once - with Bake All Dynamics button which will bake everything you have to bake in scene:


  Bake All Dynamics
      Bake all physics systems in the scene, even those of different types. Useful for baking complex setups involving interactions between different physics types.


Note that it may last longer than you expected (because of amount of data to compute).