# Restarting of the simulation from the beginning

**URL:** <https://gromacs.bioexcel.eu/t/restarting-of-the-simulation-from-the-beginning/9894>\
**Category:** User discussions\
**Created:** [August 16, 2024, 4:11am UTC](https://gromacs.bioexcel.eu/t/restarting-of-the-simulation-from-the-beginning/9894 "2024-08-16T04:11:22Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Khushboo](https://avatars.discourse-cdn.com/v4/letter/k/7cd45c/32.png) [@Khushboo](https://gromacs.bioexcel.eu/u/Khushboo)\
**Post date:** [August 16, 2024, 4:11am UTC](https://gromacs.bioexcel.eu/t/restarting-of-the-simulation-from-the-beginning/9894/1 "2024-08-16T04:11:22Z")

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GROMACS version: gromacsgpu 2022  
GROMACS modification: Yes/No  
I am running a 250ns simulation with daily runs of 30ns. However, due to power fluctuations, the simulation keeps restarting from the beginning. How can I prevent the simulation from starting over and instead continue from where it left off?

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**Author:** ![obZehn](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/obzehn/32/2629_2.png) [@obZehn](https://gromacs.bioexcel.eu/u/obZehn)\
**Post date:** [August 16, 2024, 6:45am UTC](https://gromacs.bioexcel.eu/t/restarting-of-the-simulation-from-the-beginning/9894/2 "2024-08-16T06:45:05Z")

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Dear @Khushboo

What do you mean to start over?

During the run, GROMACS produces various output files, and among these there is going to be one, which is a checkpoint file, that has the extension `*.cpt` (and possibly another one similar that is something like `*_prev.cpt`). You can continue from these checkpoint files by adding the flag `-cpi checkpoint_file.cpt` to `mdrun`, take a look at the [manual](https://manual.gromacs.org/current/user-guide/managing-simulations.html).