History of the National INFN Pool P. Mazzanti, F. Semeria INFN – Bologna (Italy) European Condor Week 2006 Milan, 29-Jun-2006

Our first experience (1997) Monte Carlo event generation. WA92 experiment at CERN: Beauty search in fixed target experiment. Working conditions: a dedicated farm of 3 Alpha VMS and 6 DecStation Ultrix. Results: events/day (0 dead time).

Then Condor came... Production Condor Pool: –23 DEC Alpha 18 Bologna 2 Cnaf (Bologna) 2 Turin 1 Rome –4 HP –6 DecStation Ultrix –5 Pentium Linux

The throughput of the 23 Alpha subset of the pool: to events/day plus events/day with the pool in Madison. We got x5 the production at zero cost! Then Condor came… (cont.)

Give me a calculator… At INFN : 1000 PCs used 8 hours/day by the owners (16 hours/day idle) 1000 * 16 = hours = 1.8 year 1.8 year equivalent CPU wasted each day!

The ‘Condor on WAN’ INFN Project Approved by the Computing Committee on February Goal: install Condor on the INFN WAN and evaluate its effectiveness for the INFN computational needs. 30 people involved.

The Condor INFN Project (cont.) The INFN Structure 27 sites More then 10 experiments on nuclear and sub- nuclear physics. Hundreds of researchers involved. Distributed and heterogeneous resources. (good frame for a grid…)

The Condor INFN Project (cont.) The first example in Europe of a national distributed computing environment

Collaboration INFN and Computer Science Dept. of the University of Wisconsin, Madison Coordinators for the project: –for Madison: Miron Livny –for INFN: Paolo Mazzanti.

General usage policy Each group of people must be able to maintain full control over their own machines.

General usage policy (cont.) A Condor job sent from a machine of a group must have the maximum access priority on the machines of the same group.

Subpools rank expression: a resource owner can give priority to requests from selected groups: GROUP_ID = “My_Group” RANK = target.GROUP_ID == “My_Group” From the group point of view the machines make a pool by themselves: a subpool.

Checkpoint Server Domains The network could be a concern with a computing environment distributed over a WAN. Policy: a job should run in the ckpt domain if local resources are available.

The INFN-WAN Pool (2000) ALPHA/OSF1 111 INTEL/LINUX 68 HP/HPUX 10 SUN/SOLARIS 11 INTEL/WNT 1 Total201

The INFN-WAN Pool (2002) ALPHA/OSF1 107 INTEL/LINUX 122 SUN/SOLARIS 6 INTEL/WNT 1 Total 235

INFN Condor Pool Allocation Time (Hours) (1999) Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan TOTAL (> 36 years)

Applications Simulation of the CMS detector. MC event production for CMS. Simulation of Cherenkov light in the atmosphere (CLUE). MC integration in perturbative QCD. Dynamic chaotic systems. Extra-solar planets orbits. Sthocastics differentials equations. Maxwell equations.

Simulation of Cherenkov light in the atmosphere (CLUE). Without Condor (1 Alpha): –20000 events/week. With Condor: events in 2 weeks (gain: x9)

Dynamic chaotic systems Computations based on complex matrix (multiplication,inversion,determinants etc.). Very CPU-bound with little output and no input. Gains with Condor respect to the only Alpha used: x3.5 to x10.

MC integration in perturbative QCD CPU-bound No input, very small output Gains with Condor: x10.

Maxwell Equations 201 jobs, each with a different value of an input parameter. Output: 401 numbers/jobs Gains with Condor compared to the only Alpha available: x11

People very very very happy!!

The Pool Today 8 checkpoint servers: Bologna,Milano,Torino,Pavia,Trieste, Padova,LNGS,Napoli. 270 CPUs 45.5 years CPU equivalent used from January to June 25th -> 91 years CPU/year

Why the pool does not grow up? Why Condor is not installed on all PCs? Is it difficult to install? Is it difficult to use? Is it difficult to maintain? We are prefer to buy new machines?

An automatic installation tool Three type of installation –server: binary and library only –client: configuration files only –Full: client+server Rpm files are built up Web interface

Server installation Only binaries and libraries Usually done on nfs or afs servers. It exports bin and lib to the clients

Client installation Install configuration files using data specified through the web interfaceCreates startup and shutdown scripts for the Condor daemons Add binaries path (from the ‘server’ installation) in the users PATH

Full installation Client + Server All the condor distribution and the configuration files on the same machine NFS and AFS are not required

Conclusion The INFN Condor Pool has been the first ‘pre-grid’ wide area distributed computing system. It is still used by people out from the ‘big science’.

Conclusion (cont.) BUT: why not Condor on each PC? We did not find the answer in 10 years…