tl;dr must be stable and persistent, always able to maintain a constant connection with the client software don't use a user's personal computer as a license server use a currently supported Microsoft OS bare-metal hardware, virtual hardware, cloud hosted - all are fine if the hardware meets the OS specifications, it meets the license server specifications configure your network and firewalls to allow the client-server communication Use an always-on, accessible server (not a user's PC) Your license server should be on a stable, persistent system that is always on and always accessible via a stable IP address or fully qualified domain name. A user’s personal system is not a good license server, unless they are only serving licenses to themselves, in which case please consider contacting your local FlexSim distributor to exchange for a standalone license. Operating System Hosting FlexSim licenses requires a currently supported version of Windows (desktop or server versions are supported). FlexSim and FlexNet do not support Windows operating systems that have reached their end-of-life. See Microsoft guidance on product lifecycle. You should perform all Microsoft Updates so that your operating system is fully patched prior to installing the license server software. In the future we hope to allow FlexSim licenses to be hosted on Linux or Mac license servers, in addition to Windows. Work toward multiplatform is ongoing. We do not currently have an estimated timeline. Server Hardware If your license server hardware meets the specifications required for the chosen Microsoft OS, it will be adequate to run the license server software. Hosting licenses is generally NOT a demanding workload. Please do not confuse these minimal license server hardware requirements with the different and more demanding system requirements for running FlexSim Simulation Software. Cloud Hosting Your license server could be hosted by a cloud provider or on premises, on a virtual machine, or a bare-metal OS. Keep in mind that your license server should be a stable, persistent server that client PCs can remain connected to. If your server setup works by creating and destroying new instances of a virtual machine each time you reboot, it is NOT suitable for use as a license server. You will lose your Trusted-Storage-based FlexSim licenses when the virtual machine is terminated. Networking, firewalls, connectivity For the client software to remain licensed, it must maintain a constant network connection to your license server. The exact details of such a configuration are up to you. If you want to limit client-server connections to the local network, allow access to the license server worldwide over a VPN, or make your licenses available over the public Internet, these are all decisions you must make and configure your network and firewalls accordingly such that your FlexSim client PCs can maintain a constant connection to the license server. Further networking guidance, including information regarding firewalls and port numbers, is found in the individual instructions for lmtools or lmadmin.

Run FlexSim "in the cloud"? Instead of provisioning a desktop or laptop PC that meets FlexSim's recommended system requirements, you may prefer for your FlexSim users to use a thin client PC which connects to a more powerful back end system that actually runs FlexSim. FlexSim does not test our products in such environments, so your user experience may vary. Meet the system requirements It is important that the remote system meet or exceed FlexSim's recommended system requirements. Usually for CPU and RAM that is not a problem. In the past, the biggest hurdle was typically graphics. Does the remote machine support hardware accelerated graphics, and support streaming those graphics to the thin client where the user is actually sitting? If the graphics are not accelerated, or if accelerated graphics can't be streamed to the user, then the system doesn't meet FlexSim's requirements and you may have a bad user experience. In the past In the past, provisioning such a system to meet FlexSim's requirements was quite a specialized combination of hardware and software. Even today not every cloud provider has the infrastructure to stream accelerated graphics. Our anecdotal experience is that such set ups are becoming more common among 3rd party cloud providers. Going forward Major players now seem to have mainstream support for hardware accelerated graphics: https://aws.amazon.com/ec2/elastic-graphics/ https://docs.microsoft.com/en-us/azure/virtual-machines/windows/sizes-gpu https://cloud.google.com/gpu/ As mentioned above, FlexSim is not targeted to these environments and the software is not tested in these environments, so your mileage may vary. Conclusion With more and more cloud providers enabling hardware accelerated graphics, there is a chance that FlexSim could work well on a cloud-based platform. If you have tried running FlexSim remotely using one of these or another cloud provider, we'd love to hear your experience. Please comment below to let us know about your setup, what worked, and what didn't.

Recommended System Requirements This article complements FlexSim's System Requirements. We'll go over each of the major components, discuss their importance to a FlexSim model, and make recommendations to help you decide on the right hardware for your situation. CPU Single Model Run A single run of a FlexSim model (ie not an experiment or optimization run) is single threaded, which means it runs on only 1 CPU core. Buying a processor with more cores won't speed up a single simulation run. To complete single model runs more quickly, use instead a processor with a faster single core clock speed (gigahertz, or cycles per second) or better efficiency (instructions per cycle). In short, for the fastest individual model runs, you want the fastest processor possible, regardless of the number of cores. Experimenter or Optimizer - Multiple Simultaneous Replications When you're doing multiple simultaneous model runs using the Experimenter or Optimizer, FlexSim takes advantage of multiple CPU cores to run simulation replications in parallel. By default, FlexSim spawns as many replications as you have cores; for example, a Quad core processor enables four single-threaded simulation runs to process simultaneously, one on each core, getting you results four times faster than by using a single core processor at the same speed/efficiency. If necessary, you can manually limit the number of concurrent replications by setting the Max Cores value from FlexSim's Main Menu under Statistics > Experimenter > Advanced tab > Max Cores input field. Each replication consumes some amount of system RAM, so if you run out of RAM before you run out of cores, it may be necessary to limit the number of cores used to run replications. Conclusion If you’re primarily doing single simulation runs, choose a faster processor speed regardless of the number of cores. If you’re primarily doing experiments, choose a processor with a high number of processing cores (and make sure your system has enough RAM to support them - see Memory below). If you’ll be doing both, choose a processor that strikes a good balance between core speed and core count. Memory Considerations Random Access Memory, or RAM, is a PC's fast "working" memory, where it stores the data and programs it is currently running (don't confuse this with your much slower hard drive, where data is stored "at rest"). Most consumer Windows computers top out at 32 or 64 GB of RAM, though Windows is capable of supporting much more when coupled with high-end hardware (see limits per OS here). Your computer is always doing many other things besides just running FlexSim. Your operating system itself has memory needs for all the processes it is constantly running. You probably have an antivirus solution, maybe a backup software, and often other utilities running invisibly in the background. Then there are all the applications you currently have open - your email, a web browser, music streaming, etc. All of these are consuming RAM. As you plan your FlexSim hardware, be aware that you should have enough RAM to run all these other applications, plus your FlexSim model, plus have a good amount of extra RAM as a buffer. FlexSim's Requirements Many FlexSim models will use less than 4 GB of RAM in a single model run, but it all depends on your simulation and data. Some large and complex models can and do go above 4 GB of RAM utilization (sometimes well above). If FlexSim's RAM utilization starts approaching a high percentage of your total available system RAM, your computer will turn sluggish or totally unresponsive as it runs out of memory and begins paging out to disk for its memory needs (which is orders of magnitude slower than RAM). A FlexSim system should have 8 GB of RAM as a minimum. For the best experience we recommend 32 GB of RAM or more. Many modern high-end consumer PCs meet this recommendation. See FlexSim's latest minimum and recommended system requirements here. Experiments and Optimizations Experiments and optimizations run several replications of your model simultaneously, so make sure you have enough total memory in your system so that each replication can hit its peak memory needs, while still leaving enough memory for the system and other running applications (OS, antivirus, other background processes, etc.). In addition, the experimenter saves statistics data for each replication by default. Each completed replication will send its statistics collectors' data to the main FlexSim thread, where it will ultimately be stored in the results database file on the hard drive. However, several stages of the transfer process require two copies of the data. In addition, all child processes can transfer data simultaneously. So, if you have a model that generates 100MB of statistics data, and you run an experiment with 8 CPUs, and all 8 CPUs finish a replication at roughly the same time, you'll need at least 1600MB (100 MB x 2 x 8) to transfer the data successfully, on top of all the other RAM utilization. Example Scenario I've developed a simulation model and now I'd like to run multiple replications using the Experimenter. Watching my simulation run normally, while monitoring FlexSim's memory usage with Windows Task Manager, I see that over the entire course of its run my simulation peaks at about 2.1 GB of RAM at its highest utilization. My computer system has 16 GB of RAM. When FlexSim is not running at all, the system uses about 20% of its resources for the operating system and other background processes. This leaves about 12.8 GB of RAM free. How many concurrent replications of FlexSim can my PC support? 12.8 GB / 2.1 GB per replication = 6.1 concurrent replications So, I might get by with allowing 6 concurrent replications of FlexSim, but I feel like 5 is a safer bet to give the system a bit of headroom, and because running the experimenter and collecting results data also requires some additional memory overhead. Since my computer has a quad-core processor and uses simultaneous multithreading (SMT) (which allows each core to run two FlexSim replications at once), FlexSim's default would be to run 8 concurrent replications. My calculations showed that 8 concurrent replications would be too many, and will probably bog down my PC, slowing or halting the entire process. I will limit the number of concurrent replications the experimenter will use by setting the Max Cores value to 5. This option is set from FlexSim's Main Menu under Statistics > Experimenter > Advanced tab > Max Cores input field. Your settings will differ from this example. Check your computer's amount of RAM, the peak memory needs of your simulation models, and your baseline RAM utilization when you're not running any simulations. Factor in a reasonable % as a buffer. Use these values to determine how many concurrent FlexSim replications your computer may support. When allowing FlexSim to use its default of running the max number of replications your CPU supports, please keep in mind that many multi-core CPUs actually run multiple threads simultaneously per core (simultaneous multithreading - SMT). To fully take advantage of all the simultaneous replications that your PC could run at once, be sure to get enough RAM for all the replications your CPU is capable of. For example, a 4-core CPU with support for SMT could run 8 simulation replications at once. Make sure you have the memory to do so! If not, be sure to use the Max Cores option to limit the number of concurrent replications. Conclusion A system meeting FlexSim's minimum RAM requirement will have enough memory for a single model run of most simulation models. If your simulations are large or complex, or if you intend on running experiments or using the optimizer, you should meet the higher recommended spec of 32 GB of RAM or more. Disk Space Requirements The FlexSim installer may be up to 1.2GB in size, depending on the FlexSim version. After installation, FlexSim's program files use up to 1.2GB of disk space. Your model files, CAD layouts, images, custom 3D shapes, import data, exported reports, and other simulation related assets that you provide will take disk space in addition to the software's installation footprint. Disk Speed Most FlexSim models will run from memory, so hard drive speed isn't really an issue. However, if you're reading/writing with files/databases while the model is running, disk speed could make a huge difference; a Solid-State Drive (SSD) is a must in that case. Alternatively, try to do data reading and writing before and after the simulation run, if possible. FlexSim recommends SSDs in general because they make every interaction with your computer feel faster and more responsive. You won't regret an upgrade from a regular, spinning hard drive to an SSD. Conclusion Consider upgrading your hard drive to an SSD if you will be reading or writing to files or databases during a model run, or to generally improve system responsiveness. Graphics Recommended Graphics The better/newer/bigger/faster the graphics processor, the better the performance. Integrated graphics, where a smaller GPU is packaged into the CPU, have gotten much better in recent years, but a discrete GPU remains the most powerful graphics solution. FlexSim works best on Nvidia GeForce RTX or GTX GPUs, but Nvidia Quadro and AMD Radeon are also good solutions. Most recent integrated graphics solutions meet FlexSim's minimum graphics requirements, but in general will not perform as well as discrete graphics. Graphics Driver Updates It is also important to note that you should keep your graphics drivers updated to the latest version. If your graphics hardware meets FlexSim's minimum requirements but you are experiencing graphical issues in FlexSim, a graphics driver update may solve the problem. Please check out this article for some common symptoms and solutions to graphics issues within FlexSim. Virtual Reality FlexSim supports Oculus Rift/Meta Quest 2, HTC Vive, and Windows mixed reality virtual reality platforms (see demo models). Be sure to meet FlexSim's higher recommended specifications if you plan to use VR. Conclusion While recent integrated graphics solutions meet FlexSim's minimum requirements, a discrete graphics solution is a better choice. For maximum performance, FlexSim recommends a recent NVIDIA GeForce RTX GPU.