# Presentation: 072969

##     ATLAS Computing.     Introduction + Overview

- Norman McCubbin (RAL)
- Computing Co-ordinator

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS Computing: Introduction + Overview

- Organisation: people/task matrix
- Main milestones
- Summary of major activities
- “Projectisation” of Computing:
- schedule, PBS;
- effort; ‘holes’; software agreements;
- hardware resources:
- National Computing Board; World-Wide Computing;
- MONARC; CERN Review

- McCubbin: von Ruden Review 26 Oct 00

## Computing organization

- simulation

- reconstruction

- database

- coordinator

- QC group

- simulation

- reconstruction

- database

- Arch. team

- Event filter

- Technical Group

- National Comp. Board

- Comp. Steering
- Group

- Physics

- Comp. Oversight Board

- Detector system

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS Detector/Task matrix

**Physics Co-ordinator: F.Gianotti      Chief Architect: D.Quarrie**

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS Computing: Introduction and Overview

- The major schedule items (with indicative dates) for the next 2-3 years are:
- Develop **framework** through series of releases, leading to first ‘fully-functional’ version by end 01.
- Profit from **TestBeam **requirements, starting this year.
- Major effort to validate **Geant4** for ATLAS, with **simulation workshop** Dec. 2000 and **Physics workshop** Spring September 2001.
- Have first version of **reconstruction software** ready (start 01) for Event Filter analysis for TDAQ TDR.
**MDC0**: 100k event ‘continuity test’ for end 01.
- Chain (G4 simulation and ATLAS code) ready for **MDC1** (“0.1% PB”) to start in 02. (Open issues: how to ‘trigger’; involvement of Regional Centres (RC))
**Computing TDR**: deliver end 02. (Open issues: date)
**MDC2**: First half 03.  “10% of 1PByte”. Must, inter alia, validate computing model. (Open issues: how to ‘trigger’; scale; collaboration with other experiments.)

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS Computing: Introduction + Overview

- Simulation:
- major effort is focussed in Geant4 (G4)   physics validation for ATLAS;
- very detailed studies (G4/G3/Test-Beam) are now in progress: G4 looks promising but of course needs tuning/refining. ATLAS results presented at several conferences/work-shops.
- close collaboration with G4 team (monthly meetings);
- ATLAS G4-physics workshop Dec. 4+5;
- major goal is G4 ‘good enough’ for Mock Data Challenge 0 (end 2001). G3 as ‘insurance’?

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS Computing: Introduction + Overview

- Reconstruction:
- first target is to have C++ versions of reconstruction working via framework (Athena) for end of this year; muon code will be MuonBox (Fortran);
- Lar code already available via Athena; MuonBox and xKalman++ have been interfaced ‘privately’ to Athena, some tidying still needed.
- these versions of recon. codes will be used (on existing Geant3 data) for TDAQ TDR. (Maybe later versions, depending on TDAQ TDR date);
- Reconstruction w/shop to assess progress Oct 24.

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS Computing: Introduction + Overview

- ‘Projectisation’ of Computing:
- Scale, scope, duration, and cost of ATLAS computing project all argue for a greater formal ‘projectisation’ of computing than has been done in previous experiments (LEP, HERA, UA1,2 , etc.)
- Indeed, my time as Computing Co-ordinator has strengthened my conviction that this is not only desirable but essential.
- Details of our planning etc. so far can be seen at: http://cern.ch/Atlas/GROUPS/SOFTWARE/OO/planning
- Considerable effort to harmonise with USA at PBS level to avoid duplication and confusion. (See presentations of Meinhard and Wenaus)
- We have prepared a first version of a schedule, which includes the major milestones mentioned above, but also gives much much more detail.

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS Computing: Introduction + Overview

- This schedule is by no means ‘final’ or complete. (e.g. ‘World-wide computing’ not yet entered in detail, and ‘dependencies’ need much more detail). But it does give significant detail through to end 2001, and is already proving valuable for Computing Steering Group (CSG): part of each (monthly) meeting is devoted to schedule ‘follow-up’.
- A first set of LHCC and ATLAS Exec. Board (EB) milestones has been defined. This list will surely grow.

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS Computing; Introduction + Overview

- PBS is used to estimate effort required to deliver the computing project.
- It is clear that the entire project (including ‘core’ software and detector-specific software) requires approx. 100 ‘full-time-equivalent’ (fte) per year from now until......  (see next slide)
- It is also clear that we have some urgent and obvious ‘vacancies’ right now.
- I have sent round (in August) a first list of ‘infrastructure’ tasks to be filled. There has been some response, but by no means enough!

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS Computing: Introduction + Overview

-   ‘Core’   effort estimate (fte’s):
-                            2000 2001 2002 2003 2004 2005
-  sub-T O T A L (1-8)         30.2  33.4  30.6   24.2  23.3  23.4
-  ======================================
-     T O T A L (1-12)           34.6  47.2  46.6   42.2  39.3  39.4
-  (1-8) includes framework, dBase, core management,...
- (1-12) adds in world-wide computing, GRID, MDC’s.
- N.B. above is requirement, we don’t have it all!

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS Computing: Introduction + Overview

- It has also been recognised for some time that computing (hardware definitely, software probably) will require, and benefit from, Computing MoU.
- This emphasises the point that CERN cannot provide the major share of these resources; they have to come from the other institutes. (CERN will provide some, of course..)
- More on the hardware side in a moment; on the software side the main benefit (in my opinion) of an MoU is to commit institutes in the same way as they feel committed by detector MoU.

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS Computing: Introduction + Overview

- Since the signing of MoU is some way off, and because the whole idea is new for computing, we have been developing the idea of “**software agreements**”, which could, eventually, form part of Computing MoU.
- The **policy paper** on software agreements has been approved by the National Computing Board, and by the ATLAS CB in June 2000.
- We have just launched, through the NCB, a list of tasks which could be covered by ‘core’ software agreements.
- Idea of software agreement (swa) is to get formal institute commitment. Thus it helps ATLAS; it may also help ATLAS members in arguing for resources in their institute.
- Hope is to get first swa (Control Framework with USA) signed by end of the year.

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS Computing: Introduction + Overview

- On hardware resources, there is a lot of work going on, stimulated by the following (related) points:
- as mentioned above, much of the money (and effort) for computing hardware and infrastructure will have to come from outside CERN; scale is such that Funding Agencies will have to be asked ‘officially’ for support;
- a possible model for ‘World-Wide Computing’ was discussed already at the time of the ATLAS and CMS Computing TPs: major computing centres (‘Regional Centres’) in a few regions which act as computing ‘hubs’ for their region(s). Thus you do not ‘copy from CERN’ every time; required data is copied to your Regional Centre ‘once’, etc. etc.
- This thinking has been elaborated in considerable detail in the MONARC project. (RDxx: participation from all LHC experiments)
- It is also now clear that estimates of resource requirement will be one of the most important outcomes of the **CERN Review.**

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS Computing: Introduction + Overview

- H.Hoffmann launched idea of CERN Review of LHC Computing in second half of 1999. Announced at Marseille workshop in September 99.
- Aims:
- assess state of work and preparations in experiments and IT;
- provide input for Computing MoUs, which should be put in place in 2001;
- recommend actions and in particular common actions between experiments and IT Division that will help to achieve desired goals within existing resources;
- first draft of report December 2000 (?).

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS week Oct 2000: Introduction to Computing

- Review organised as Steering Committee (Chair S.Bethke) and three ‘technical panels’:
- Panel 1: ‘world-wide computing model’: chair D.Linglin, ATLAS: A.Putzer, L.Perini
- Panel 2: ‘software’: chair M.Kasemann, ATLAS: D.Barberis, M.Bosman
- Panel 3: ‘management and resources’: chair M.Calvetti, ATLAS: J.Huth, H.Meinhard
- Inevitably some overlap between panels, particularly 1 and 3.
- Steering Committee meets monthly (since Jan. 00)
- All LHC experiments and IT have now had several sessions (presentations and discussions) with each of the Panels. This interaction is now more or less complete. Panel 2 (internal) report is finished.

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS Computing: Introduction + Overview

-  Panels 1 and 3 will, in due course, produce up-to-date estimates of LHC computing resources required and costs.
- CERN Management has indicated that it will not make any statement on what part of LHC computing costs will be covered by CERN until it has had a chance to consider the findings of the CERN Review.
- For Steering Committee to do its job properly (digest information from panels; think; write) will still take a couple of months. A verbal (progress) report has just been presented by Hans Hoffmann to the October Resource Review Board.

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS Computing: Introduction + Overview

-  Much of the subject matter discussed by Panels 1 and 3 of the CERN Review is also of prime concern to the ATLAS National Computing Board (NCB), Chairman: Alois Putzer (Heidelberg)
- Stimulated in part by CERN Review and various GRID activities, NCB has now formed w/groups which, as a first step, will gather information (‘what’s going on’) on GRID, Regional Centres etc.
- For several (related) reasons the whole topic of ‘world-wide computing’ has, rightly, moved up the agenda in the last few months.
- In ATLAS we have used a plausible estimate of event size (1MB) and trigger rate (100Hz) for several years. (As have CMS) Following the very detailed Physics (TDR) and Trigger (TP) studies, we have much more refined and understood  estimates.... But they are higher (‘270x2’ at 10^33). This is being addressed, vigorously.

- McCubbin: von Ruden Review 26 Oct 00

## ATLAS Computing: Introduction + Overview

- There has been a lot of progress since the January ‘00 ‘von Ruden’:
- framework/architecture
- Reconstruction Code
- Simulation
- organisational infrastructure (planning etc.)
- And the USA contribution has been very significant.
- ATLAS Computing effort needs your continuing and ongoing support.

- McCubbin: von Ruden Review 26 Oct 00