2 November 2001 2Jürgen Knobloch
LHC Computing Challenges
• Data volume• Data rate• Data complexity• CPU power• World wide distributed analysis• Long project lifetime• Competition
2 November 2001 3Jürgen Knobloch
Rare Phenomena - Huge Background
9 or
ders
of
mag
nitu
de!
The HIGGS
All interactions
2 November 2001 4Jürgen Knobloch
CPU Requirements
• Complex events– Large number of signals– “good” signals are covered
with background
• Many events– 109 events/experiment/year– 1- 25 MB/event raw data– several passes required
Need world-wide:
7*106 SPECint95 (3*108 MIPS)
2 November 2001 5Jürgen Knobloch
Complex Data = More CPU Per Byte
les.
rob
ert
son
@ce
rn.c
h
Estimated CPU Capacity required at CERN
0
1,000
2,000
3,000
4,000
5,000
199
8
199
9
200
0
200
1
200
2
200
3
200
4
200
5
200
6
200
7
200
8
200
9
201
0
Jan 2000:3.5K SI95
Other experiments
LHCLHC
K SI95
Moore’s law – some measure of the capacity technology advances provide for a constant number of processors or investment
2 November 2001 6Jürgen Knobloch
Data Volume
• Raw data storage: 7 PB/a• Simulated data : 3 PB/a• World wide tape: 28.5 PB/a
50 CD-ROM
= 33 GB
6 cm
10 P
B =
> 1
8 km
2 November 2001 7Jürgen Knobloch
The 4 LHC Experiments
CMS
ATLAS
LHCb
2 November 2001 8Jürgen Knobloch
On-line System• Multi-level trigger• Filter out background• Reduce data volume• 24 x 7 operation
Level 1 - Special Hardware
Level 2 - Embedded Processors
40 MHz
40 MHz (1000 TB/sec)
(1000 TB/sec)
Level 3 – Farm of commodity CPUs
75 KHz 75 KHz (75 GB/sec)
(75 GB/sec)5 KHz5 KHz (5 GB/sec)
(5 GB/sec)100 Hz 100 Hz (100
(100 MB/sec)MB/sec)
Data Recording &
Offline Analysis
2 November 2001 9Jürgen Knobloch
World-wide collaboration
Europe: 267 institutes, 4603 usersElsewhere: 208 institutes, 1632 users
2 November 2001 10Jürgen Knobloch
Regional Centres - a Multi-tier Model
les.
rob
ert
son
@ce
rn.c
h
CERNTier2
Lab aUni b
Lab c
Uni n
Lab m
Lab b
Uni bUni y
Uni x
PhysicsDepartment
Desktop
Tier 1
USAFermiLab
UKRutherford
FranceIN2P3/Lyon
ItalyCNAF/Bologna
NLNIKHEF
2 November 2001 11Jürgen Knobloch
CERN Computer Centre Today
2 November 2001 27Jürgen Knobloch
Compilers & Systems
• Removing legacy UNIX systems• Concentrate on LINUX on Intel• Solaris on SUN as second platform• Most new developments in C++• Still legacy FORTRAN software to keep alive• Debugging tools on LINUX not yet at the
required level