Update of LHC experiments Computing & Software Models

1. Update of LHC experiments Computing & Software Models Selection of slides from last week’s GDB http://indico.cern.ch/conferenceDisplay.py?confId=197803

2. Background Ian.Bird@cern.ch • Requested by the LHCC in December: need to see updated computing models before Run 2 starts • A single document to: • Describe changes since the original TDRs (2005) in • Assumptions, models, technology, etc. • Emphasise what is being done to adapt to new technologies, to improve efficiency, to be able to adapt to new architectures, etc. • Describe work that still needs to be done • Use common formats, tables, assumptions, etc • 1 document rather than 5

3. Timescales Ian.Bird@cern.ch • Document should describe the period from LS1 – LS2 • Estimates of evolving resource needs • In order to prepare for 2015, a good draft needs to be available in time for the Autumn 2013 RRB, so needs to be discussed at the LHCC in September: • Solid draft by end of summer 2013 (!)

4. Opportunities Ian.Bird@cern.ch • This document gives a framework to: • Describe significant changes and improvements already made • Stress commonalities between experiments – and drive strongly in that direction • Significant willingness to do this • Describe the models in a common way – calling out differences • Make a statement about the needs of WLCG in the next 5 years (technical, infrastructure, resources) • Potentially review the organisational structure of the collaboration • Review the implementation: scale, quality of service of sites/Tiers; archiving vs processing vs analysis activities • Raise concerns: • E.g. staffing issues; missing skills;

5. Draft ToC Ian.Bird@cern.ch • Preamble/introduction • Resource needs and expected evolution • Technology review and outlook • Challenges – the problem being addressed • Consequences for computing • Experiment computing models • Distributed computing • Computing services • Common software activities and strategies • Collaboration organisation and management

6. Experiment specific chapters • Many topics need to be covered in this document: • Data models – types of data, event sizes, relationships, etc. • The operational workflows are strongly correlated to these. • Data flows, replication and placement policies. • Optimal use of resources to provide the best possible physics throughput. • Role of Tiers and sites with emphasis on functionalities and services required. • Anticipated event rates and data streams in Run-2. • Non-event data handling. • For example evolution of database usage and technologies, e.g. Oracle, Frontier, Hadoop, CVMFS... • Software evolution. • Further software optimization in terms of processing speed, event sizes, parallelization etc.. • Data preservation. • ... and several more.. • An important point is to demonstrate clearly also the progress we made from the Computing TDRs until now, not just the envisaged progress towards Run2. • Also, clearly identify the envisaged commonalities between experiments and potential input from the wider scientific community.

7. Status • Drafts of all chapters in preparation • Bernd Panzer, Ian Bird, John Harvey • 4 LHC experiments computing projects • Experiment specific chapters based on common template • I am drafting the LHCb chapters • First drafts to be circulated within working group by end of next week • We are late, unclear if I can circulate internally first • Time for discussion and refinement during June but basically frozen by mid-July • I would have preferred to have an LHCb editorial team, but: • We are all so busy and time is short • Requires weekly F2F interaction with other experiments