Ansys Lumerical products come with a GUI and a solve license. See Lumerical product components and licensing and list of licensed features by product for more information.
The solver component allows running simulations on your machines. This article explains how many 'solve' licenses are required for various simulations, license types, and resource configurations. 'Solve' licenses are job and core/thread counted.
Overall, the number of ‘solve’ licenses depend on the amount of resource required for your project. For simulations running on CPU, it depends on the number of cores. For simulations running on GPU, it depends on the number of streaming multiprocessors (SMs). More instances of simulations also require additional ‘solve’ licenses, but license sharing is available in some cases, which is described below.
Enterprise and HPC license consumption
Single jobs
CPU jobs
One enterprise solve license allows running a simulation job using up to 4 cores.
Extra cores can be utilized by using Ansys HPC licenses, either in packs or workgroup increments. You can use the Ansys HPC Licensing Calculator tool to determine how many licenses is required to run your simulation or parameter sweeps. In the calculator, the number of cores per analysis should be calculated by processes*threads.
Example – license consumption
- Running a single (1) simulation job on a local machine using 32 cores. This requires:
-
1 enterprise solve license plus 28 Ansys HPC Workgroup increments
or
1 enterprise solve license plus 2 HPC Pack increments
- Distributing a simulation across 4 machines with 32 cores (4 * 32 = 128 cores). This requires:
-
1 enterprise solve license plus 124 HPC Workgroup increments
or
1 enterprise solve license plus 3 HPC Pack increments.
GPU jobs
Simulations using the FDTD solver can run on the GPU starting in 2023 R2. One enterprise license allows running a simulation job using up to 4 streaming multiprocessors (SMs).
Additional resource can be utilized by using Ansys HPC licenses in the same way as CPU jobs.
For GPU jobs, parts of the computation, such as meshing and script commands, still uses the CPU. Therefore, the number of licenses required is determined by either the SMs in the GPU(s), or the number of cores on the CPU set to be used for the job, whichever one needing the higher license count.
For more information on GPU computing, see the Knowledge Base article Getting Started with Running FDTD on GPU.
Example – license consumption
- Running a single (1) simulation job on a local machine using 32 cores, and a GPU that has 16 SMs. This requires:
1 enterprise solve license plus 28 Ansys HPC Workgroup increments
or
1 enterprise solve license plus 2 HPC Pack increments - Running a single (1) simulation job on a local machine using 16 cores, and a GPU that has 16 SMs. This requires:
1 enterprise solve license plus 12 Ansys HPC Workgroup increments
or
1 enterprise solve license plus 2 HPC Pack increments
Parametric sweeps and license sharing
License sharing allows the same ‘solve’ license to be shared amongst multiple concurrent jobs, useful for parametric sweeps. Without license sharing, each concurrent job will need 1 solve license.
With an enterprise license, parametric sweep with HPC licensing allows Ansys HPC licenses to be used in place of extra ‘solve’ licenses. You can use either the Ansys Parametric Licensing Calculator tool, or the license estimation window to calculate how many licenses you need to run your parameter sweep according to configured resources.
Parametric sweep with HPC licensing is available in the following scenarios:
- For all products and solvers when running on the local computer (localhost), local and remote MPIs, and job schedulers, through the GUI.
- For the FDTD solver only, when running on a job scheduler, either through lumslurm.
Example – license consumption
- Running a parameter sweep on the local computer (localhost) using 6 cores per simulation and 4 concurrent simulations for a total of 24 cores used to run the job. An example Resource Configuration window for this is shown below.
This will require:1 enterprise solve license plus 32 Ansys HPC Workgroup increments
or
1 enterprise solve license plus 4 Ansys HPC Pack increments
Standard (business and academic) solve license consumption
Academic licenses behave the same way as business licenses in terms of license consumption, with the key difference being that academic licenses come with 4 solve licenses per product.
Single-job license consumption
CPU Jobs
A single standard solve license allows you to run one simulation job using up to 32 cores. To run a job with more than 32 cores, an additional solve license is required for each increment of 32 cores.
Example – license consumption
- Running a single (1) simulation job on a local machine using 32 cores. This requires:
1 solve license
-
Distributing a simulation across 4 machines with 32 cores each (4 * 32 = 128 cores). This requires:
4 FDTD/varFDTD solve licenses
-
Distributing a simulation across 4 machines with 8 cores each (4 * 8 = 32 cores). This requires:
1 FDTD/varFDTD solve license
GPU jobs
Simulations using the FDTD solver can run on the GPU starting in 2023 R2. One standard license allows running a simulation job using up to 16 streaming multiprocessors (SMs). An additional solve license is required for each increment of 16 SMs.
For GPU jobs, parts of the computation, such as meshing and script commands, still uses the CPU. Therefore, the number of licenses required is determined by either the SMs in the GPU(s), or the number of cores on the CPU set to be used for the job, whichever one needing the higher license count.
For more information on GPU computing, see the Knowledge Base article Getting Started with Running FDTD on GPU.
Example – license consumption
- Running a single (1) simulation job on GPU a local machine using 32 cores and a 20 SM GPU. This requires:
2 solve licenses
Parametric sweeps and license sharing
License sharing allows the same ‘solve’ license to be shared amongst multiple concurrent runs. Without license sharing, each concurrent job will need 1 solve license. Support for standard license sharing has been added starting with the 2022 R1.1 release.
Standard (business and academic) license sharing allows the solve license to be used for concurrent jobs of up to 32 cores. If more than 32 cores are needed in total, each concurrent job needs its own solve license. See example section below for more details. The license estimation window is used to calculate how many licenses you need to run your parameter sweep according to configured resources.
Standard license sharing is unsupported on Windows when using the Intel MPI. Please use Microsoft MPI or Local Computer as the Job launching preset on Windows.
In addition to the above restriction, standard license sharing is available in the following scenarios:
- Only for Ansys Lumerical FDTD™, Ansys Lumerical MODE ™, and Ansys Lumerical Multiphysics ™ when running on the local computer (localhost) through the GUI on CPU.
- For the FDTD solver only, when running on the local computer through the command line. There is no MPI support when running through the command line.
The availability of license sharing for standard license is displayed in the license estimation utility on the bottom of the Resource Configuration window.
Example – Standard license sharing in command line
To run multiple concurrent simulations through the command line, follow the instructions below.
- Open a Windows command prompt or terminal in Linux.
- Change the directory to the location of your FDTD simulation files.
- Run the simulations using the FDTD engine executable.
The concurrent simulations are now running with license sharing.
The examples below show how 4 concurrent simulations, each with 4 threads can be executed. In this example, only one ‘solve’ license is consumed due to license sharing.
Windows:
"C:\Program Files\Lumerical\[[verpath]]\bin\fdtd-engine.exe" -t 4 simulationfile1.fsp simfile2.fsp simfile3.fsp simulationfile4.fsp
Linux:
/opt/lumerical/[[verpath]]/bin/fdtd-engine-mpich2nem -t 4 sweepfile1.fsp sweepfile2.fsp sweepfile3.fsp sweepfile4.fsp
Example – license consumption with standard license sharing
- Running a parameter sweep on the local machine using 6 cores per simulation and 4 simulations running concurrently, with a total of 24 cores running the job.
The resource configuration for the local machine is set to processes=6 and capacity=4. The resource configuration window indicates if license sharing is enabled (true) or not (false) for each resource.
With standard license sharing, this requires:1 solve license to run the job with 4 concurrent sweeps
- Running a parameter sweep on the local machine using 6 cores per simulation and 6 concurrent simulations. This simulation requires a total of 36 cores, which is over the limit to which standard license sharing applies. Therefore, each concurrent simulation now requires its own solve license.
Therefore, this setup requires:6 solve licenses to run the job with 6 concurrent sweeps
License consumption calculation tools
Ansys HPC licensing calculator
The Ansys HPC Licensing Calculator is a web tool that calculates the number of HPC increments and packs required for enterprise licensing. You can use it with your setup to determine the number of HPC packs or workgroup increments required.
The number cores per analysis can be obtained by processes*threads. If you wish to run on multiple resources each with a different number of cores, you need to compute the average number of cores per active engine instance rounded up to the nearest core. The average core is calculated by dividing the sum of the Total Cores and the number of active resources.
License estimation utility
Starting in 2025 R1.3, a license estimator utility is available in the resource configuration window. This tab allows you to check how many licenses each resource needs, and how many licenses are required if a parameter sweep is executed on all active resources simultaneously.
For GPU resources, a manual entry of the number of SMs in the GPU is required, which can be done by double clicking on the cell in the “SM Estimate” column in GPU resources. For local resources, the number of SMs can be found using the gpuspecs script command.
For both enterprise and standard licenses, the number of licenses required for both running a single job, and running a sweep with the set capacity on each resource is estimated. In addition, the number of licenses required for running either CPU or GPU parametric sweeps on all active resources is displayed at the bottom.
For enterprise license, the number of required Ansys HPC workgroup increments and Ansys HPC packs is displayed. This number should match the number obtained from the Ansys HPC Licensing Calculator.
For standard license, the number of required solve licenses is displayed.
The license estimation feature can be accessed by script commands getlicenseestimate and getlicenseestimateallactiveresources, and through lumslurm.