[gmx-users] Checkpointing

[Mark Abraham]

----- Original Message -----
From: Jack Shultz <js at drugdiscoveryathome.com>
Date: Wednesday, February 3, 2010 2:36
Subject: [gmx-users] Checkpointing
To: Discussion list for GROMACS users <gmx-users at gromacs.org>, Andrey Voronkov <av at drugdiscoveryathome.com>

> We have mdrun integrated into our distributed computing project. When
> your users suspend or close the manger it checkpoints, so when they
> open again it continues mdrun where it left off. However, when users
> reboot, it starts from the beginning. We are using this command line
> to execute the work.
> 
> mdrun.exe (-v -x -c -o md.pdb -e -cpo md.next -cpi md.cpt -
> deffnm md)

If you're using this input line always, then you're getting what you're asking for - an mdrun that begins from the state in md.cpt. Since you're never updating that, it doesn't change.

Try not stipulating different -cpo and -cpi and see what the native coping mechanism is. Otherwise, you'll have to write a bunch of scripting logic to decide which .cpt to use each restart.

Mark

> I have a seperate checkpoint for output so after this simulation we
> can extend the workunit. Should we try using this append option?
> 
> Checkpoints containing the complete state of the system are 
> written at
> regular intervals (option -cpt) to the file -cpo, unless option -cpt
> is set to -1. A simulation can be continued by reading the full state
> from file with option -cpi. This option is intelligent in the 
> way that
> if no checkpoint file is found, Gromacs just assumes a normal 
> run and
> starts from the first step of the tpr file.
> 
> With checkpointing you can also use the option -append to just
> continue writing to the previous output files. This is not 
> enabled by
> default since it is potentially dangerous if you move files, but if
> you just leave all your files in place and restart mdrun with exactly
> the same command (with options -cpi and -append) the result will be
> the same as from a single run. The contents will be binary identical
> (unless you use dynamic load balancing), but for technical reasons
> there might be some extra energy frames when using checkpointing
> (necessary for restarts without appending).
> 
> 
> 
> 
> -- 
> Jack
> 
> http://drugdiscoveryathome.com
> http://hydrogenathome.org
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