[gmx-users] mdrun with append option

Sai Pooja saipooja at gmail.com
Tue Feb 1 18:01:24 CET 2011


I am doing a manual replica exchange(generalized hamiltonian rem) after
every mdrun. If the replica exchange is successful, then I "exchange
checkpoint files". For example, consider the following:

Simulation parameters:....................B1.........B2
Replicas(coordinates and velocities):.R1.........R2

 0. Tpbconv to extend simulation time ( using -s, -o and -nsteps ONLY)
1. Mdrun run - 500 steps = 1ps
2. Attempt exchange - NOT SUCCESSFUL
3. Exchange implementation: SKIP
4.Continue to next step

.....
0. Tpbconv to extend simulation time ( using -s, -o and -nsteps ONLY)
1. Mdrun run - 500 steps = 1ps
2. Attempt exchange - If successful, exchange
3. Exchange Implemented by - exchanging checkpointing files
4. Continue to next step

0. Tpbconv to extend simulation time ( using -s, -o and -nsteps ONLY)
1. Mdrun with exchanged .cpt files -NOW this is where the problem shows..
      i) The log, xtc files are not appended when beginning after a step
with a successful exchange attempt:*According to Mark's previous mail, this
could be a result of mismatch in ensembles. Which means that the .cpt is
ignored - implying that the mdrun in B1 DOES NOT start from R2.*

Therefore, to make R1 run in B2 and R2 run in B1, do I need to supply .cpt
to tpbconv instead of mdrun after a successful exchange step?

To summarize:
APPENDING HAS NOW BECOME A SECONDARY CONCERN, WHAT I AM INTERESTED IN IS A
SUCCESSFUL MANUAL REPLICA EXCHANGE RUN AS POINTED OUT ABOVE.

I hope my dilemma is clear now.

Pooja


On Tue, Feb 1, 2011 at 11:42 AM, Justin A. Lemkul <jalemkul at vt.edu> wrote:

>
>
> Sai Pooja wrote:
>
>>  From the website:
>>  "If you change the integrator or ensemble, you should pass the checkpoint
>> file to tpbconv only, not to mdrun, since the state might change and thus
>> output files can not be appended."
>>
>>
>
> Are you changing the integrator, ensemble, and/or other settings?  If not,
> this statement does not apply.  For a simple -append after extending via
> tpbconv, this is not applicable.
>
>
> So now instead of supplying the checkpoint file to mdrun I supply it to
>> tpbconv... does this assure that the simulations start from the
>> coordinates/velocities specified by the .cpt file?
>>
>>
>
> For a simple extension, you do not pass the .cpt file to tpbconv.
>
>
> http://www.gromacs.org/Documentation/How-tos/Extending_Simulations#Version_4
>
>
>    Thanks Mark. So if the simulation doesn't start from the checkpoint
>>    file, from where are the initial coordinates velocities etc. taken
>>    from?... the trajectory files?
>>
>
> Mark's previous message already answered this.
>
> -Justin
>
>          Also, I could not find the environment variable... and I am not
>> sure
>>    how to use one.
>>         Pooja
>>    On Tue, Feb 1, 2011 at 3:03 AM, Mark Abraham
>>     <Mark.Abraham at anu.edu.au <mailto:Mark.Abraham at anu.edu.au>> wrote:
>>
>>        On 1/02/2011 7:50 AM, Sai Pooja wrote:
>>
>>>        I think I have figured out the reason. It is because I am
>>>        carrying out replica exchange (manual) after every mdrun. If
>>>        the exchange occurs, I exchange the checkpoint files, extend
>>>        the simulation by 500 steps and continue. The new simulation
>>>        starts from exchanged cptfile. It seems that whenever the
>>>        exchange occurs, the earlier log,traj files are not appended.
>>>        They are instead overwritten. the obv solution is to save and
>>>        index these files with the relevant replicas everytime an
>>>        exchange occurs.
>>>
>>
>>        This would have been good to know earlier. If replica-exchange
>>        leads to the ensemble of the .tpr not matching the ensemble of
>>        the .cpt, then IIRC 4.5.3 mdrun will refuse to start from the
>>        .cpt, which means the subsequent mdrun will start from the .tpr
>>        only. Certainly a non-appending mdrun prints a warning (or
>>        error, I forget which) message to the log file, but perhaps the
>>        use of -append (erroneously) doesn't do that. Please have a look
>>        and see if that is the issue. There is an environment variable
>>        that can be set to tell mdrun that you (think you) know what you
>>        are doing mismatching .tpr and .cpt.
>>
>>        Mark
>>
>>
>>          However, i have a more general question. Since mdrun still
>>>        runs with the exchanged checkpoint files and starts from the
>>>        point where the previous run ended, can I be assured that an
>>>        exchange has been affected - since tpr files correspond to the
>>>        "replica-box" and cpi to the most recent exchanged replicas?
>>>                 Pooja
>>>
>>>        On Mon, Jan 31, 2011 at 2:33 PM, Sai Pooja <saipooja at gmail.com
>>>         <mailto:saipooja at gmail.com>> wrote:
>>>
>>>
>>>            I manually index checkpoint files after every mdrun. What
>>>            troubles me is the randomness with which -append fails/works.
>>>                         For eg, I have a simulation which runs from 3ns,
>>> 1ps in 1
>>>            mdrun. Now oddly enough, the logfile starts from 1184ps(in
>>>            the end, I do remember the one starting from 0 but that
>>>            was overwritten it seems) and the rest is appended uptil
>>>            the 3000ps step. Why would append work from 1184ps to
>>>            3000ps but not for the previous ones?Could it have
>>>            anything to do with the network/cluster? If that is the
>>>            case is it safer to create a new file everytime and then
>>>            concatenate them after say every 100ps?
>>>                         Pooja
>>>            On Sat, Jan 29, 2011 at 6:52 PM, Mark Abraham
>>>            <Mark.Abraham at anu.edu.au <mailto:Mark.Abraham at anu.edu.au>>
>>>
>>>            wrote:
>>>
>>>                On 30/01/2011 10:39 AM, Sai Pooja wrote:
>>>
>>>>                I would be happy to supply more information.. if
>>>>                someone could please look into this.. otherwise I
>>>>                will have to switch to storing every file and then
>>>>                just concatenating them which seems like a rather
>>>>                roundabout way of doing it.
>>>>
>>>
>>>                As I suggested a few emails ago, are you sure that
>>>                -cpi file exists? If your numerical suffixes are
>>>                indexing restarts, then unless you've done some manual
>>>                copying that you haven't told us about, it won't. Your
>>>                filename scheme seems a bit contorted - like you're
>>>                trying to do the work that GROMACS 4.5.x will just do
>>>                for you if you let it.
>>>
>>>                Otherwise, you'll have to do some detective work with
>>>                gmxcheck on the -cpi to see what might be the issue.
>>>
>>>                In your case, an initial
>>>
>>>                mdrun -deffnm rex_3
>>>
>>>                (perhaps save some copies while you're experimenting)
>>>                and subsequently
>>>
>>>                tpbconv -extend <blah> -f rex_3 -o rex_3
>>>                mdrun -deffnm rex_3 -append
>>>
>>>                will work and be much simpler than whatever you're
>>>                trying to do with filenames :-)
>>>
>>>                Mark
>>>
>>>
>>>
>>>>                On Fri, Jan 28, 2011 at 4:37 PM, Sai Pooja
>>>>                <saipooja at gmail.com <mailto:saipooja at gmail.com>> wrote:
>>>>
>>>>                    This is the command:
>>>>                                         nbs submit -command
>>>>                    "(/usr/local/gromacs/4.5.1/bin/mdrun_mpi -s
>>>>                    rex_3.tpr -e rex_3 -c after_rex_3 -cpi restart3
>>>>                    -cpo restart3 -ap
>>>>                    pend -g rexlog3 -x rextraj3);" -nproc 1 -name
>>>>                    "GENHAM-DIHEDRAL-3" -mail start end
>>>>                                         Pooja
>>>>
>>>>                    On Fri, Jan 28, 2011 at 4:20 PM, Mark Abraham
>>>>                    <Mark.Abraham at anu.edu.au
>>>>                     <mailto:Mark.Abraham at anu.edu.au>> wrote:
>>>>
>>>>                        On 29/01/2011 3:56 AM, Sai Pooja wrote:
>>>>
>>>>                            Hi,
>>>>                            I am using tpbconv and mdrun to extend a
>>>>                            simulation. I use it with the append
>>>>                            option but the files still get
>>>>                            overwritten or erased. Can someone help
>>>>                            me in this regard?
>>>>                            Pooja
>>>>                            Commands (in python)
>>>>                            cmd = '(%s/tpbconv -extend %f -s
>>>>                            rex_%d.tpr -o rex_%d.tpr)'
>>>>                            %(GROMPATH,dtstep,i,i)
>>>>                                 os.system(cmd)
>>>>                                 time.sleep(1)
>>>>                                 cmd  = 'nbs submit -command "'
>>>>                                 cmd += '(%s/mdrun_mpi -noh
>>>>                            -noversion -s rex_%d.tpr -e rex_%d -c
>>>>                            after_rex_%d -cpi restart%d -cpo
>>>>                            restart%d -append -g rexlog%d -x
>>>>                            rextraj%d >/dev/null); '
>>>>                            %(GROMPATH,i,i,i,i,i,i,i)
>>>>                                 cmd += '" '
>>>>                                 cmd += '-nproc 1 '
>>>>                                 cmd += '-name "GENHAM-DIHEDRAL-%d" '%(i)
>>>>                                 cmd += '-mail start end '
>>>>                                 cmd += '-elapsed_limit 16h >> rexid'
>>>>                                 os.system(cmd)
>>>>
>>>>
>>>>                        More useful for diagnostic and
>>>>                        record-preservation purposes is to construct
>>>>                        the cmd string and print it to stdout (or
>>>>                        something).
>>>>
>>>>                        At the moment it is far from clear that your
>>>>                        -cpi file exists for the new run.
>>>>
>>>>                        Mark
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>>>>                           gmx-users at gromacs.org
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>>>>
>>>>
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>>>>
>>>>
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>>>> you shall discover.
>>>>
>>>>
>>>>
>>>>
>>>>                --                 Quaerendo Invenietis-Seek and you
>>>> shall discover.
>>>>
>>>
>>>
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>>
>>
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>>
> --
> ========================================
>
> Justin A. Lemkul
> Ph.D. Candidate
> ICTAS Doctoral Scholar
> MILES-IGERT Trainee
> Department of Biochemistry
> Virginia Tech
> Blacksburg, VA
> jalemkul[at]vt.edu | (540) 231-9080
> http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
>
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-- 
Quaerendo Invenietis-Seek and you shall discover.
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