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