10-Jan-00 CERN Building a Regional Centre A few ideas & a personal view CHEP 2000 – Padova 10 January 2000 Les Robertson CERN/IT

CERN 10-feb-00 - #2les robertson - cern/it Summary  LHC computing system topology  Some capacity and performance parameters  What a regional centre might look like  And how it could be staffed  Political overtones & sociological undertones  How little will it cost?  Conclusions

CERN 10-feb-00 - #3les robertson - cern/it The Basic Topology Cern – Tier 0 Tier 1 FNAL RAL IN2P3 622 Mbps Tier2 Lab a Uni b Lab c Uni n 622 Mbps 155 mbps Department GLA EDI DUR

CERN 10-feb-00 - #4les robertson - cern/it  Tier 0 – CERN  Data recording, reconstruction, 20% analysis  Full data sets on permanent mass storage – raw, ESD, simulated data  Hefty WAN capability  Range of export-import media  24 X 7 availability  Tier 1 – established lab/data centre or green-fields LHC facility  Major subset of data - raw and ESD  Mass storage, managed data operation  ESD analysis, AOD generation, major analysis capacity  Fat pipe to CERN  High availability  User consultancy – Library & Collaboration Software support Tier roles

CERN 10-feb-00 - #5les robertson - cern/it Tier 2 and the Physics Department  Tier 2 – smaller labs, smaller countries, hosted by existing data centre  Mainly AOD analysis  Data cached from Tier 1, Tier 0 centres  No mass storage management  Minimal staffing costs  University physics department  Final analysis  Dedicated to local users  Limited data capacity – cached only via the network  Zero administration costs (fully automated)

CERN 10-feb-00 - #6les robertson - cern/it More realistically - a Grid Topology Cern – Tier 0 Tier 1 FNAL RAL IN2P3 Tier2 Lab a Uni b Lab c Uni n Department   

CERN 10-feb-00 - #7les robertson - cern/it Capacity / Performance Based on CMS/Monarc estimates (early 1999) Rounded, extended and adapted by LMR CERN Tier 1 1 expt. Tier 1 2 expts. Tier 2 1 expt. Capacity in 2006 Annual increase # cpus #disks CPU (K SPECint95) Disk (TB) Tape (PB) (includes copies) <10 I/O rates disk (GB/sec) tape (MB/sec) WAN bandwidth Mbps optimistic MB/sec

CERN 10-feb-00 - #8les robertson - cern/it Tier 1 RC Two classes –  A - Evolved from an existing full-service data centre  B - New centre – created for LHC Class A centres need no gratuitous advice from me Class B will have a strong financial incentive towards –  Standardisation among experiments, Tier 1 centres, CERN  Automation of everything  Processors, disk caching, work scheduling  Data export/import   Minimal operation, staffing –  Trade off mass storage for disk + network bandwidth  Acquire excess capacity (contingency) rather than fighting bottlenecks, explaining to users 

CERN 10-feb-00 - #9les robertson - cern/it What does a Tier 2 Class B centre look like? Computing & Storage Fabric built up from commodity components  Simple PCs  Inexpensive network-attached disk  Standard network interface (whatever Ethernet happens to be in 2006) with a minimum of high(er)-end components  LAN backbone  WAN connection and try to avoid tape altogether  Unless there is nothing better for export/import  But think hard before getting into mass storage  Rather mirror disks, cache data across the network from another centre (willing to tolerate the stress of mass storage management)

CERN 10-feb-00 - #10les robertson - cern/it Scratchpad  Co-location – Level 3, Storage Networks Inc.  KISS  Take technical risks with the testbed  Favour reliability and cost-optimisation (e.g. JIT ) with the production system