Stop and restart

Stop and restart#

An important feature when running a simulation is the ability to stop and restart it. This section explain how you can do it with TRUST.

Stop a Running Calculation#

When using TRUST, your calculation will automatically stop if it has reached:

  • the end of the calculation time.

  • the maximal allowed cpu time.

  • the maximal number of iterations.

  • the threshold of convergence.

You may use the my_data_file.stop file, if you want to stop properly your running calculation (i.e. with all saves).

When the simulation is running, you can see the 0 value in that file. To stop it, put a 1 instead of the 0 and at the next iteration the calculation will stop properly.

When you don’t change anything to that file, at the end of the calculation, you can see that it is writen Finished correctly.

Save#

TRUST makes automatic backups during the calculation. The unknowns (velocity, temperature,…) are saved in:

  • one .xyz file, written:

  • at the end of the calculation.

  • but, user may disable it with the specific keyword EcritureLectureSpecial 0 added just before the Solve keyword.

  • one (or several in case of parallel calculation) .sauv files, written:

  • at the start of the calculation.

  • at the end of the calculation.

  • each 23 hours of CPU, to change it, uses periode_sauvegarde_securite_en_heure keyword (default value 23 hours).

  • user may also specify a time physical period with dt_sauv keyword.

  • periodically using tcpumax keyword for which calculation stops after the specified time (default value \(10^{30}\)). Use it for calculation on CCRT/TGCC and CINES clusters for example.

Note

By default, the name for the .sauv files is filename_problemname.sauv for sequential calculation, filename_problemname_000n.sauv for parallel calculation (one per process). The format of theses files is binary and the files are completed during successive saves.

You can change the behaviour using the following keywords just before the solve instruction:

sauvegarde binaire|xyz filename .sauv|filename .xyz

with xyz: the .xyz file is written instead of the .sauv files.

Note

You can use sauvegarde_simple instead of sauvegarde where the .sauv or .xyz file is deleted before saves, in order to keep disk space:

sauvegarde_simple binaire|xyz filename .sauv|filename .xyz

For more information, go see the TRUST Keyword Reference Manual.

Resume#

To resume your calculation, you may:

  • change your initial time, the new initial time will be the real final calculation time of the previous calculation (see the .err file).

  • change your final calculation time to the new wanted value.

  • add the following block just before the Solve keyword:

reprise binaire|xyz filename .sauv|filename .xyz

Note

Instead of reprise keyword, you can use resume_last_time where tinit is automatically set to the last time of saved files (but you may change tmax):

resume_last_time binaire|xyz filename .sauv|filename .xyz

You can resume your calculation:

  • from .sauv file(s) (one file per process): you can only resume the calculation with the same number of equations on the same number of processes.

  • or from a .xyz file: here you can resume your calculation by changing the number of equations solved and/or with a different number of processes.

Note

You can run a calculation with initial condition read into a save file (.xyz or .sauv) from a previous calculation using Champ_Fonc_reprise or read a into a MED file with Champ_Fonc_MED.

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