1. Status report on LHC_2: ATLAS computing
Tetsuro Mashimo
International Center for Elementary Particle Physics
(ICEPP), The University of Tokyo
on behalf of the LHC_2 project team
Workshop FJPPL’07
May 9, Japan

2. LHC_2 in the year 2006
Collaboration between the IN2P3 Computing Center in Lyon (CC-IN2P3) and the ‘Regional Center’ at ICEPP, the University of Tokyo
Purpose: various R&D studies for WLCG (Worldwide LHC Computing Grid)
In WLCG, CC-IN2P3 as a ‘Tier-1’ center and ICEPP as a ‘Tier-2’ center
The Tier-2 center at ICEPP is for the ATLAS experiment only
Especially important:
Establish a network connection with a high bandwidth and efficient data transfer to produce physics results quickly
It is challenging to fully exploit the available bandwidth due to the large latency for a long distance connection (Round Trip Time (RTT) ~ 280msec)

3. ATLAS Detector Construction & Installation
A few PB of raw data (each year)
Diameter m
Barrel toroid length 26 m
End-cap end-wall chamber span 46 m
Overall weight Tons
Detector sensors M channels

4. Distributed computing for LHC

5. R. Jones / ATLAS

6. LCG-France sites Supported LHC experiments
All sites also support other virtual organizations

7. LCG-France sites Tier-2: GRIF Tier-2: GRIF CEA/DAPNIA CEA/DAPNIA LAL
LLR
LPNHE
IPNO
Tier-2: GRIF
CEA/DAPNIA
LAL
LPNHE
Tier-3: IPHC
Strasbourg
Ile de France
Tier-3: IPNL
Nantes
Tier-2: Subatech
Tier-3: LAPP
Clermont-Ferrand
Tier-2: LPC
Annecy
Lyon
Tier-1: CC-IN2P3
AF: CC-IN2P3
Marseille
Tier-3: CPPM

8. ATLAS FR Cloud Tier-2: GRIF CEA/DAPNIA LAL LPNHE Tier-3: LAPP
Pekin
Tokyo
Roumanie
Ile de France
Nantes
Tier-3: LAPP
Tier-2: LPC
Annecy
Tier-1: CC-IN2P3
AF: CC-IN2P3
Marseille
Tier-3: CPPM

9. LHC_2 in the year 2006 (cont’d)
Members in the project team (* leader)
French group
Japanese group
D. Boutigny*
IN2P3
T. Mashimo*
ICEPP
F. Malek
I. Ueda
G. Rahal
H. Matsumoto
F. Hernandez
H. Matsunaga

10. Budget plan in the year 2006 Item Euro Support-ed by k Yen Travel
1,000
160
Nb travels 2
2,000
CNRS
320
ICEPP
Per-diem
237
22.7
Nb days 10
2,370
227
Total
4,370
547

11. Activities in 2006 Mainly tests for data transfer
In the overall ATLAS framework:
`SC4’ (Service Challenge 4)
Also special tests
Communications mainly by
(Visits in February and March 2007)

12. SC4 (Lyon → Tokyo) RTT (Round Trip Time) ~ 280 msec
The available bandwidth limited to 1 Gbps
Linux kernel 2.4, no tuning, standard LCG middleware (GridFTP)
~ 20 MB/s (15 files parallel, each 10 streams)
Not satisfactory (packet loss)

13. Test with iperf (memory to memory)
Linux kernel
Congestion control
TCP Reno vs. BIC TCP
Try also PSPacer (from AIST, Tsukuba)
Best result: BIC TCP + PSPacer
Tokyo → Lyon: >800 Mbps (with 2 streams): shown below

14. Summary for iperf results
SL(C)4 (kernel 2.6 with BIC TCP): much better in congestion control than SL3 (kernel 2.4)
Software Pacer (PSPacer by AIST) in addition gives a stable and good performance
1 stream
10 streams
Lyon → Tokyo
0-5 MB/s
2-20 MB/s
Tokyo → Lyon
10-15 MB/s
44-60 MB/s
1 stream
2 to 8 streams
Lyon → Tokyo
45 MB/s
Tokyo → Lyon
70 MB/s
100 MB/s

15. LHC_2 in the year 2007 (cont’d)
Members increased (new members in green, * leader)
French group
Japanese group
E. Lançon*
CEA
T. Mashimo*
ICEPP
F. Malek
IN2P3
I. Ueda
G. Rahal
H. Matsunaga
F. Hernandez
J. Tanaka
D. Boutigny
T. Kawamoto
J. Schwindling
S. Jézéquel

16. Year 2007
Not only purely technical R&Ds, but also studies for data movement in view of physicists’ point of view
The available network bandwidth will increase (probably this year)
A new computer system has been installed at ICEPP and more man power is soon available for technical studies
More intensive R&D for this year toward the LHC start-up

17. Tape Robot
Disk Arrays
PC Servers

18. Budget plan in the year 2007 Item Euro Support-ed by k Yen Travel
1,000
160
Nb travels 3
3,000
CNRS
480
ICEPP
Per-diem
237
22.7
Nb days 15
3,555 12
272
Nb Travels 1
CEA 5
1,185
Total
8,740
752