If a System Coupling simulation is interrupted, it is possible to re-start it using System Coupling restart. To use System Coupling restart, restart point(s) must be available from a previous simulation. In a steady state coupled analysis, you can save restart points after each coupling iteration by the following command in the python file:
DatamodelRoot().OutputControl.Option = 'EveryIteration'
In a transient coupled analysis, you can save restart points after each coupling step by:
DatamodelRoot().OutputControl.Option = 'EveryStep'
Using these commands, the System Coupling simulation should write a restart point after each successful coupling iteration (or step). If the restart files are successfully written, under the "SyC" sub-directory, you should see files named Restart_iter<#>.h5, where # is the index of the corresponding coupling iteration, or Restart_step<#>.h5, where # is the index of the corresponding coupling step. At the end of a System Coupling simulation (if it completes successfully), System Coupling lists the available restart points at the end of the scLog.log file.
Each participant has their own files stored for System Coupling restart. For Forte, the files are stored under WorkingDirectory\forte\Restart_Files\, where "forte" is the name of the object for Forte participant. The number at the end of each file name refers to the coupling iteration (or step) index.
Tip: To do a System Coupling restart, one must have at least one restart point ready. This means that at least one coupling iteration (or step) must be completed and the relevant restart files are in place.
To execute a system coupling restart from a certain restart point, write a command
to open the restart point in the Python script before the Solve()
command. For example, in a steady state coupled analysis,
# To start from the restart point generated at the end of the 5th coupling iteration Open(CouplingIteration = 5) Solve()
In a transient coupled analysis,
# To start from the restart point generated at the end of the 3rd coupling step Open(CouplingStep = 3) Solve()
Tip: If the files related to the requested restart point are not available or have been deleted, either under "SyC" or a participant's relevant directory, or if you try to Open a non-existent restart point, System Coupling will throw an error and will come to a hard stop.
If a System Coupling simulation is interrupted for any reason, restart won't occur automatically. You must execute the Python script with the commands discussed above.
Note: System Coupling restart is different from a restart of Forte simulation by the Reuse Point. These are two different concepts with different purposes. Forte's Reuse Point, as detailed in Step 1: Set up Forte Project for System Coupling, allows Forte simulation to restart from it in the subsequent coupling iterations. Its main purpose is to save computational time.
During a restart run, Forte will leave the existing results prior to the restart point intact and will create new subfolders that continue the progression after the restart.
For more general information regarding usage of System Coupling restart, refer to Restarting a Coupled Analysis in the System Coupling User's Guide.