Quick Start Guide

This guide is for the impatient who wants to run and test a minimal VeloC environment on a single node to get a first impression of how it works. It can be achieved in three-steps:

Download and Install

$git clone -b 'veloc-x.y' --depth 1 https://github.com/ECP-VeloC/veloc.git <source_dir>
$cd <source_dir>
$./auto-install.py <install_dir>

Note: replace x.y with the latest stable version available on github.


Create and switch to the temporary working directory /tmp/work. Open test.cfg and add the following contents:

scratch = /tmp/scratch
persistent = /tmp/persistent
mode = async

Run VeloC

Open a terminal and run the heatdis example application using two MPI ranks:

$export LD_LIBRARY_PATH=<install_dir>/lib
$export PATH=<install_dir>/bin:$PATH
$mpirun -np 2 <source_dir>/build/test/heatdis_mem 256 test.cfg

If the run was successful, the scratch and persistent directories will be populated with checkpoint files of the form heatdis-x-y.dat, where is is the rank and y is the iteration number. Also, a log file should have been created where the active backend (the VELOC service running on each node which responsible for checkpoint management) displays important information: /dev/shm/veloc-backend-<hostname>-<uid>.log.

Now, delete one of the checkpoints with the highest version from both directories, then run the same command again. The application should restart from the checkpoint version immediately preceding the highest version and continue running to completion. After the second run, the directories should be populated with the same checkpoint files as in the case of the previous run.

Congratulations, this concludes the quick start guide!