[gmx-users] why files are so large?

[Justin Lemkul]

On 4/28/13 8:04 AM, Albert wrote:
> Hello:
>
>    I am using the following settings for output file:
>
> dt              = 0.002         ; Time-step (ps)
> nsteps          = 2500000000    ; Number of steps to run (0.002 * 500000 = 1 ns)
>
> ; Parameters controlling output writing
> nstxout         = 5000000               ; Write coordinates to output .trr file
> every 2 ps
> nstvout         = 5000000               ; Write velocities to output .trr file
> every 2 ps
> nstfout         = 0
> nstxtcout       = 50000
> nstenergy       = 500000        ; Write energies to output .edr file every 2 ps
> nstlog          = 500000        ; Write output to .log file every 2 ps
>
>
> and I obtained following warnings from grompp:
>
> NOTE 2 [file md.mdp]:
>    This run will generate roughly 2791985478365075968 Mb of data
>
>
> however, when I set
> nstxout=0
> nstvout=0
> nstoout=0
>
> I obtained following informations:
>
> This run will generate roughly -9066 Mb of data
>
> why it file size is negative? Moreover, my nstxout is very large, I don't know
> why the file is so big and no matter how did I change nstxout, nstvout, the
> files size doesn't change at all. it always claimed:
>
>
>    This run will generate roughly 2791985478365075968 Mb of data
>

This looks like a pretty clear bug to me, especially the negative file size, 
which cannot possibly make sense.  What version of Gromacs is this?

-Justin

-- 
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Justin A. Lemkul, Ph.D.
Research Scientist
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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