Title: La Politique du tout PC au CERN
1La Politique du tout PC au CERN
CUIC Arcachon 21-22 juin 2000 Les
Robertson CERN/IT Genève
2Sommaire
- Le problème
- La stratégie
- Les difficultés
3Le problème
4Architectures operating systems supported at
end 1999
Digital Unix
SPARC
Solaris
MIPS
AIX
The legacy of ten years of RISC computing
Alpha
Windows 2000
Irix
Windows 95
Windows NT
Linux
Power PC
MAC-OS
Intel IA-32
PA-RISC
HP-UX
5- Combien darchitectures et systèmes
dexploitation sont vraiment nécessaire? - Combien coûte le support?
- Combien vaut la diversité?
- Comment imposer des limitations de choix dans un
environnement de recherche scientifique ?
6CERN - The European Organisation for Nuclear
ResearchThe European Laboratory for Particle
Physics
- Fundamental research in particle physics
- Financed by 20 European countries
- 6,000 users (researchers) from all over the world
- LHC accelerator under construction
- Proton-proton collider
- 27 km of super-conducting magnets
- Target date for first beams - 2005
- Four experiments
- 2000 physicists, 150 universities
7CMS detector - as big as a 6-storey
office block, - costing FF 2.000M - 1 PetaByte
of filtered data per year
8The LHC Detectors
CMS
ATLAS
3.5 PetaBytes / year 108 events/year
LHCb
9Performance or Throughput?
- High Throughput Computing
- mass of modest problems
- throughput rather than performance
- resilience rather than ultimate reliability
- Ten years of experience in exploiting
inexpensive mass market components - But we need to marry these with inexpensive
highly scalable management tools - Much in common with data mining, Internet
computing facilities,
1010-20K cpus?
Non-LHC
10K SI951200 processors
LHC
technology-price curve (40 annual price
improvement)
11Non-LHC
LHC
technology-price curve (40 annual price
improvement)
12lmr for Monarc study- april 1999
13 LHC physics facility 4 experiments 2 M
SPECint95 10-20K processors 2 PByte disk gt20 K
disks
lmr for Monarc study- april 1999
14Summary of the problem
- HEP is using far too many operating systems
- in many cases with only slightly different
functionality or hardware cost benefits - and at a high cost for users and support teams
- The scale of LHC computing -
- massive numbers of processors/boxes
- integration of regional computing centres and
CERN - ? problem is how to manage on this scale
while limiting costs of equipment, management
support - We must reduce the diversity
- while retaining flexibility
- to use low-cost, mass market components
- and adapt rapidly to changing physics needs
15La stratégie
16Opportunity
- PCs Linux Windows offer an historic
opportunity to reduce the solution set - Costs and performance
- PCs will consistently be among the very best
price/performers for HEP codes - They may not be the fastest,but they are fast
enough - Linux -a non-proprietary operating system
compatible with the recent Unix history - Windows a mass market alternative widely used
on the desktop
17Policy
- Restrict ourselves to PC hardware with Linux
or Windows 2000 - Develop a migration plan -
- progressively freeze support for other
Unixes,announcing end-dates which are
reasonable for old experiments, - strongly discourage further investments in RISC
systems by current and future experiments - install large Linux public facility, testbed for
future experiments - Concentrate investment in Linux and Windows
- bring support up to the standards of proprietary
Unixes - tackle the problems of scaling the management and
performance of physics farms and desktops - seek HEP-wide consensus
18But do not be unrealistic ----
- This is a convergence policy
- which looks realistic now
- and will provide a single starting point for LHC
computing - but we can be sure that the industry will not
stand still, and we shall sooner or later have to
expand the systems and architectures supported
Digital Unix
SPARC
AIX
MAC-OS
WNT
Solaris
Alpha
Linux
Irix
Intel IA-32
Intel IA-64
- - - ?
Windows 2000
MIPS
Power PC
Windows 95
Linux
HP-UX
PA-RISC
19Les difficultés et l'état de la migration
20Difficulties - I
- Physics (almost) entirely Unix based
- Linux is not quite ready
- (Too) wide a choice of kernels, compilers
- Poor debugging
- Different versions supported by different
applications - Complex packages (Oracle, AFS) better go with
the standard platform - Stability problems under load
- Who provides in-depth, on-site Linux systems
support? - Solution
- Standard Linux Package certified for all CERN
applications - Solaris/SPARC for special purposes
- Open posts for Linux experts
21Difficulties - II
- In a research environment
- Easy to estimate the costs of systems support
- Hard to estimate the cost of application
migration - The application experts have already moved on
- The developers have other (more interesting)
problems to solve - The problem is not only to port the code
- but (more important) to acquire confidence in the
physics results - Compiler, architecture, old bugs
- But there are signs that LinuxIntel are as good
as any! - In the past, the production use of multiple
architectures was an important factor in finding
bugs
22Current Status Physics
- For older experiments
- Strong resistance to aggressive migration
proposal - Now aiming at complete freeze on all proprietary
Unixes during 2003 - For future experiments (not yet collecting data)
- General agreement, but reserve position on
alternative platform for validation - For new experiments collecting data now
- Easy to calculate the benefits
- Have already completed migration
23Current Status other applications
- Engineering applications
- Aggressive migration plan to Windows NT/2000
Linux, with some residual SUN - Major exception is mechanical CAE (Euclid
Digital Unix) - Administration
- Database (Oracle) on SUN
- Clients Web-based (Netscape)
- Strong pockets of MAC resistance led by the
Directorate
24Conclusions
- Les besoins énormes du LHC exigent la
standardisation et lutilisation des composants
bon-marché - Opportunité Linux Windows 2000 avec Intel
IA32/64 Ethernet - Grande inertie (résistance?) de la part des
 vielles expériences - il faudra 4 années
pour terminer la migration - Mais déjà plus de la moitié des systèmes
installés et 75 de la capacité sont
Linux/Intel