Computational Steering on the GRID Using a 3D model to Interact with a Large Scale Distributed Simulation in Real-Time Michael Grønager, PhD UNI-C / Virtual Reality Center Present: Niels Bohr Institute

2 Overview The GRID in 7 minutes… Computational Steering Examples: Interactive Molecular Dynamics Interactive Fluid Dynamics OpenLB – an open source Lattice-Boltzmann solver

3 A quick example Use Private Certificate to generate a time limited “Proxy” Log in to the Grid Define a job: /bin/echo “Hallo Grid” (demo) Wait for completion…

4 The GRID What is: “The Grid”? - except for a Buzz word… Analogy: “The Electrical Power Grid” The Globus Toolkit

5 Quoted from globus.org The Grid refers to an infrastructure that enables the integrated, collaborative use of high-end computers, networks, databases, and scientific instruments owned and managed by multiple organizations. Grid applications often involve large amounts of data and/or computing and often require secure resource sharing across organizational boundaries, and are thus not easily handled by today’s Internet and Web infrastructures.

6 CERN

7 Storage – Raw recording rate 0.1 – 1 GBytes/sec Accumulating at 5-8 PetaBytes/year 10 PetaBytes of disk Processing – 200,000 of today’s fastest PCs

8 NorduGrid A Scandinavian production Grid More than 2200CPUs More than 30 sites (Grid monitor demo)

9 Computational Steering The ability to interact with a simulated physical model by changing border conditions, parameters or state. This means: Fast interaction times < 10s Intuitive user interface Physical representation of the data And to get this we need: Interactive parallel algorithms Lots of computers with fast network A lot of money or… …resource sharing The perfect candidate for the GRID!

Example: Interactive Molecular Dynamics VMD / NAMD 1 ported to GRID environments … Lets start the job … Setup: Client contacts Resource Broker A worker node (or cluster) is selected to match requirements Job is submitted Opens a SSH tunnel back to Client (this Laptop) using Private/Public keys Starts NAMD Client starts VMD Connects to tunneled port Steering established 1. See: University of Illinois at Urbana-Champaign:

Interactive Fluid Dynamics Traditional Navier-Stokes solvers not meant for interaction: Important (manual) preprocessing step building an optimal mesh. Hard to parallelize No Open Source code available The alternative: Lattice-Boltzmann Method Easy to change border conditions on the fly Easy to parallelize No Open Source code available – yet … … easy to implement OpenLB True 3D Lattice Boltzmann solver Uses ParaView for interaction and data visualization Uses OpenSceneGraph for Virtual Reality interface Aim is to run OpenLB interactively on the GRID on more than 1000CPUs

Questions? Sign up for a hands on Grid tutorial Tuesday the 8 th of June at the Niels Bohr Institute. Mail to: /