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Info

Worked Example:

We explain the model installation and the process of running of a forecast experiment on the ECMWF Atos Sequana XH2000 HPC facility (hpc2020). 

  • All model sources, data files and configuration scripts that are required for the worked example experiment described in this guide can be found on the ECMWF web site here: https://sites.ecmwf.int/openifs/openifs-data/ (only registered OpenIFS users will be given access)
  • For users with access to the ECMWF HPC facility we provide an internal filepath location for the data packages (without the model source code). 
  • In our example the model will be installed into $HOME/openifs-48r1/ as a default location.
  • The example forecast experiment will be set up in directory $OIFS_EXPT/ab2a/

It is important to note that the installation process on hpc2020 will not directly translate to alternative systems. To address this we present details about a docker install in the last section of this guide.

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Create your local installation of OpenIFS 48R1.1 48r1 by downloading and extracting the tarball containing the model source package.

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  • 21 3-D OpenIFS forecast-only tests with and without chemistry
  • 1 SCM test (based on TWP-ICE)

-j is an optional argument that allows the user to define the number of threads used to create and build openifs, e.g.

Code Block
languagebash
themeMidnight
$OIFS_TEST/openifs-test.sh -cbt -j 16

which will perform the create and build step using 16 threads

  • If -j is not supplied as a command line argument, as in the above argument, the number of threads will default to the IFS build options for 48r1, i.e. 
    • 64 threads for ATOS
    • 8 threads for all other systems
  • If -j argument is present, then the command line number of threads takes precedence over the defaults for any system 
    • The default of 8 threads can be increased for larger systems. Such an increase may speed up the build. For advice on this please liaise with the system administrator.
    • It is important to note that 8 threads can be problematic for older and lower spec systems. For example, it will not work with a 4 core intel m3. In this case reduce the number of threads to 2 for example. 
Info

In addition to the command line options defined above (-cbt) , openifs-test.sh invokes some default ecbuild options and allows a user to add ecbuild options from command line using the -- notation, e.g., $OIFS_TEST/openifs-test.sh -cbt --without-single-precision. Openifs-test - build options describes some of these options.

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