Hi everyone
Does anybody know how to solve the COMSOL Warning "MUMPS is switching to out-of-core mode." ? it take really long time to run the analysis.I tried courser mesh for this case but it didn't work. I don't know what the problem is.
Dear Javad,
Let me try to give you a not very formal answer: MUMPS is a direct solver, and it requires quite a lot of RAM memory because to diagonalize the matrix containing all the nodal equations of your model all the matrix is stored on RAM. Therefore, if the memory size needed to store/manipulate the data of your problem is bigger than the RAM available in your system, then you can not solve the problem with a direct solver. To overcome that limitation there are some clever algorithms able to load only parts of the matrix on RAM while storing the rest of the matrix on your HD/SSD. When that happens you enter in the MUMPS out-of-core function mode, and since RAM can talk much faster and efficiently to your processor than HD/SSD can, then the out-of-core mode is rather slow in comparison.
To avoid that, either you reduce the number of degrees of freedom of your problem or you increase the RAM of your system. Alternatively, you can explore the use of an iterative solver, which tend to use much less RAM memory for the same problem.
Kind regards,
Julian
You are running in single pc or workstation or in server (Cluster computing mode)?
Ritabrata Dasgupta
Thanks for your answer. It's in Single PC.
I tried Iterative Linear System Solver GMRES and it worked while there was no switching out of core mode.
Interested in this question. What I want to know is whether this warning impacts the result. Despite showing this warning, the Comsol gives a solution.
One thing is clear for certain that it's better to use this option only when you know that the stored solutions of your model will definitely exceed your PC's RAM.
Lets say you are storing solution at each second and your model running 4000 steps, there will be 4000 stored solutions and they will take all the RAM space during solution, which may exceeds your RAM. So if this happens you can turn on "out-of-core" option to specifically allow the solver to use the HD space.
If you have low RAM then the PARDISO solver is recommended than MUMPS.
For more information you can follow this thread:
https://www.comsol.kr/forum/thread/25451/out-of-core-mumps
Use PARDISO to utilize the full core benefit of COMSOL. however if you have more than 32 cores you need to use server version.
MUMPS is utilizing all the RAM and your problem needs more RAM. Use COMSOL 4.4 or later and the issue is settled.
Dear Javad,
Let me try to give you a not very formal answer: MUMPS is a direct solver, and it requires quite a lot of RAM memory because to diagonalize the matrix containing all the nodal equations of your model all the matrix is stored on RAM. Therefore, if the memory size needed to store/manipulate the data of your problem is bigger than the RAM available in your system, then you can not solve the problem with a direct solver. To overcome that limitation there are some clever algorithms able to load only parts of the matrix on RAM while storing the rest of the matrix on your HD/SSD. When that happens you enter in the MUMPS out-of-core function mode, and since RAM can talk much faster and efficiently to your processor than HD/SSD can, then the out-of-core mode is rather slow in comparison.
To avoid that, either you reduce the number of degrees of freedom of your problem or you increase the RAM of your system. Alternatively, you can explore the use of an iterative solver, which tend to use much less RAM memory for the same problem.
Kind regards,
Julian
IS MY COMPUTER SPECS FOR WORK WITH COMSOL? I am studying mechatronical engineering, I am modeling the COMSOL wrench example , my laptop has this specs:
ASUS ROGUE STRIX SCAR model G531GT
BUS SPEC PCI EXPRESSS 3.0 (8.0 GT/S)
CPU: INTEL CORE i7 9750H 3.6 gHZ
6 CORES 12 threads
RAM : 2* 16 = 32 Gb KINGSTONE DDR4 PC4 2666 CL19260
GRAPHICS NVIDEA GEFORCE GTX 1650 SIZE 4GBBytes TYPE GDDR5 BUS 128 BITS
- Badges
- Science topic