Critical Issues in Distributed Computing Jeff Templon NIKHEF ACAT’07 Conference Amsterdam, 26 april 2007

Jeff Templon – Grids : Interaction and Scaling, ACAT’07 Amsterdam, Conceptual Fragmentation u Function: n High-throughput system? n Massive on-demand bursty system? u Definition : plurality n # machines n # users n # communities n # admin domains n # geographical locations u Each has different level of requirements/effort for users/providers

Jeff Templon – Grids : Interaction and Scaling, ACAT’07 Amsterdam, Management on User Dimension u Relevant parameters: n VO n “groups” n “roles” n “attributes” u Proxy is used for all, but proxy is for A/A, not for parameter passing u Different subsystems react to proxy content in different ways n “ address” : for is fine, but use of domain to infer employer...

Jeff Templon – Grids : Interaction and Scaling, ACAT’07 Amsterdam, Distributed Data Management u Where is the data? u Synchronization n User’s head n Expt catalog n Grid Catalog n Local SRM catalog n Disk u Management : private replicas, file migration and deletion, permission propagation...

Jeff Templon – Grids : Interaction and Scaling, ACAT’07 Amsterdam, Support

Jeff Templon – Grids : Interaction and Scaling, ACAT’07 Amsterdam, Bottom Line (Experiments) u For MC production : grid is solved and working u For Analysis : grid is in its infancy n Very few people are really trying it on grid (CERN Analysis Facility?) u Big problem : grid projects focussed on computation; storage turns out to be the real problem n Organization and management very hard n “Dark Storage” n Inflation of AODs by physicists : storage already full! Can’t compute because nowhere to store answer! u Google sees similar problems!

Jeff Templon – Grids : Interaction and Scaling, ACAT’07 Amsterdam, Bottom Line (Middleware) u No good solution yet for how to manage middleware activity n CERN-only : too HEP n EGEE : no control (groups do what they want) n (Open Grid Foundation == string theory) n Commercial : paradigm mismatch u Basic stuff working, which is a miracle (thanks to LCG project)

Jeff Templon – Grids : Interaction and Scaling, ACAT’07 Amsterdam, Bottom Line (cross discipline) u Other dutch groups are starting active takeup n Medical imaging n Library & social sciences n Radio Astronomy u Challenge to bring grid and these people together n Sort of like having your grandmother drive to the supermarket in a Sherman tank... u Success of BIG GRID (our T1 funding) will be judged (by dutch gov’t) by how well we do here