<span class="n">make</span> <span class="n">g</span><span class="o">++</span> <span class="c1"># build LAMMPS for your platform</span>
</pre></div>
</div>
<p>Second, use a restart filename which contains ”.mpiio”. Note that it
does not have to end in ”.mpiio”, just contain those characters.
Unlike MPI-IO dump files, a particular restart file must be both
written and read using MPI-IO.</p>
<p>Restart files can be read by a <a class="reference internal" href="read_restart.html"><span class="doc">read_restart</span></a>
command to restart a simulation from a particular state. Because the
file is binary (to enable exact restarts), it may not be readable on
another machine. In this case, you can use the <a class="reference internal" href="Section_start.html#start-7"><span class="std std-ref">-r command-line switch</span></a> to convert a restart file to a data
file.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">Although the purpose of restart files is to enable restarting a
simulation from where it left off, not all information about a
simulation is stored in the file. For example, the list of fixes that
were specified during the initial run is not stored, which means the
new input script must specify any fixes you want to use. Even when
restart information is stored in the file, as it is for some fixes,
commands may need to be re-specified in the new input script, in order
to re-use that information. Details are usually given in the
documentation of the respective command. Also, see the
<a class="reference internal" href="read_restart.html"><span class="doc">read_restart</span></a> command for general information about
what is stored in a restart file.</p>
</div>
<hr class="docutils" />
<p>The optional <em>nfile</em> or <em>fileper</em> keywords can be used in conjunction
with the “%” wildcard character in the specified restart file name.
As explained above, the “%” character causes the restart file to be
written in pieces, one piece for each of P processors. By default P =
the number of processors the simulation is running on. The <em>nfile</em> or
<em>fileper</em> keyword can be used to set P to a smaller value, which can
be more efficient when running on a large number of processors.</p>
<p>The <em>nfile</em> keyword sets P to the specified Nf value. For example, if
Nf = 4, and the simulation is running on 100 processors, 4 files will
be written, by processors 0,25,50,75. Each will collect information
from itself and the next 24 processors and write it to a restart file.</p>
<p>For the <em>fileper</em> keyword, the specified value of Np means write one
file for every Np processors. For example, if Np = 4, every 4th
processor (0,4,8,12,etc) will collect information from itself and the
next 3 processors and write it to a restart file.</p>
</div>
<hr class="docutils" />
<div class="section" id="restrictions">
<h2>Restrictions</h2>
<p>This command requires inter-processor communication to migrate atoms
before the restart file is written. This means that your system must
be ready to perform a simulation before using this command (force
fields setup, atom masses initialized, etc).</p>
<p>To write and read restart files in parallel with MPI-IO, the MPIIO
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