Memory management with mental ray - Part 2

32bit and 64 bit OS
When it comes to memory, There are 2 different types of operating systems , 32 bit  and 64 bit.
64 bit has a the ability to reach more memory  on the system over the 32.
Note: 32 OS bit (including MAC) will only reach about 1.8 - 2 GB of RAM , even if you have more than that installed on your machine.

Adjusting the OS Virtual memory
Virtual Memory can be far larger the actual physical memory installed on the machine. The benefit is that it gives the software the impression that there is more memory than it was actually built in the computer.
This type of memory requires that the memory be swapped into disk in order to restart later. It can be somewhat time consuming.

As soon as you go beyond the actual physical memory that is installed on the machine, you will get some sort of performance drop, but the benefit would be you actually finish the render and doesn’t fail on you.
General rule of thumb, use double the amount of physical memory as your virtual memory.

Memory limit settings
If it’s not defined in the scene, mental ray will fall back on a built in memory that is somewhat high, in some cases the memory is not able to fulfill this memory limit request and it will die with memory error.
It is very critical that it’s set to reasonable value, so it will have enough memory on top of that limit available for the operating system. This will be very useful in the case of tight memory situation where mental ray can have some room to operate on.

Comments

[Jorge]

So, what do you recomend to render more than 50 millions of particles with mental ray?
Is there any workflow to deal with scenes with very high number of polygons or particles??

[Wlip]

In my experiance will Maya on OS X 32bit reach precisely 2.72GB of memory before it takes the whole render down! Sometimes less depending on the scene/texture/shader/settings etc. but never beyond 2.72GB. Mental standalone for OS X exists on a 64bit version, right? If that's the case memory is not a problem ;)