The answer to this question depends upon whether you will be executing the WRF EMS for research or real-time forecasting purposes. For real-time use, you need as much computer power as you can afford, with a premium placed on fast multi-CPU Linux systems with at least 4GB of physical memory. The amount of memory should be commensurate with CPU performance. That's just the nature of NWP as chances are that you will always want to run the model at higher resolutions over a larger computational domain with the most accurate (and expensive) physics and dynamics. For research purposes you will still want all the best for your runs; however, you will not need to make as many compromises as speed of the machine is not as critical of an issue since you are not up against any deadlines to get the model forecast completed. Finally, if you plan on running nested simulations consider increasing the amount of physical memory even further.

Minimum system needed for running the WRF EMS:

• A relatively current Linux distribution, but not too current – The WRF EMS has been tested on Red Hat Enterprise, Fedora, CentOS, SuSe, and Ubuntu distributions, although the use of Ubuntu has required some changes to the (dash/bash) interpreter in the past. Other distributions will probably work; however, it’s simply too difficult to keep up with all the releases and updates. There is typically a lag before the EMS developer can install a newly released OS and run the tests. So just stick with what works.
  
  
• Enough physical memory to run the benchmark case - While the minimum amount of physical memory needed is ~2 Gb, it is strongly suggested that machines have a minimum of 4 Gb for real-time modeling to avoid paging and swapping issues. In general, if you have less than 4 Gb of memory then consider increasing your system resources. Besides, memory is relatively inexpensive.

• 8 Gb of available disk space – This requirement pertains to the installation of the EMS only. Of course, running an NWP model can use up a significant amount of disc space so this requirement should be considered as an absolute minimum.

• The T|C shell must be installed on the system – Linux purists may get all upset about this requirement but that’s just the way it is for now; however, it will likely change in the future. Note that in many current Linux releases, the default is not to install tcsh, so you may have to install it separately. The ems_install.pl routine will check whether it is installed and provide an error message.

• The EMS user must be using a T|C shell – If you are installing the EMS under a known user then they must be running csh or tcsh; otherwise horrible things may happen such as the EMS failing to run. And you don’t want that to happen.  There are ways around this requirement but we’re not going there right now.

• Root permission and/or write permission on a large disc partition  - The ems_install.pl routine was designed to be run a root user. You will have the opportunity to assign ownership to an existing or new user during the processes.  That said, the EMS can be installed by an existing user provided the user has write permission on the drive were the EMS will reside.

 

The results of benchmark runs with both the NMM and ARW cores should provide some guidance in determining what type of performance to expect from your system relative to others.

The ARW core benchmark results are available.

The NMM core benchmark results are available.