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RAL Storage

This workshop report summarizes the use of dCache for managing storage access at Tier 1 and T2 sites, with plans to expand to multiple locations. The report includes details on current deployments, challenges faced, operational experiences, and collaboration efforts within the storage community.

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RAL Storage

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  1. RAL Storage J Jensen <j.jensen@rl.ac.uk> Contributions from Tier 1 (D Ross, A Sansum, S Traylen) Storage Workshop, CERN 5-7 April 2005

  2. Who we are RAL – http://www.clrc.ac.uk/Activity/RAL; GridPP – http://www.gridpp.ac.uk/ • GridPP Tier 1 • http://www.gridpp.ac.uk/tier1a/ • GridPP Storage middleware group • Supporting deployment to T2s throughout UK • http://storage.esc.rl.ac.uk/ • RAL Atlas Datastore • http://www.e-science.clrc.ac.uk/web/services/datastore

  3. GridPP Storage Goals • SRM 1 to tape and disk at Tier 1 • SRM 1 to disk at Tier 2s • Disk pool management

  4. SRB used for DC04 • SRB also currently used to tapestore • Used by many non-HEP experiments • CMS and ATLAS now using the SRM to Tier 1

  5. Service Challenge 2 • Getting 75 MB/s from CERN • But seeing 3-3.5 Gb/s over LAN • Investigating… • Lightpath • Got it at last moment • Underprovisioned?

  6. dCache Installations UK • GridPP Tier 1 • Derek ROSS • Deployed three dCache-with-SRM • Production • Service Challenge • JRA1 • GridPP Storage • Owen SYNGE and Jiří MENCÁK • Deployed three dCache-with-SRM • Test • Test • Test

  7. Current Deployment at RAL Yesterday Today

  8. dCache Installations UK, cont’d • Several Tier 2s installing dCache • Edinburgh • Manchester • Lancaster • Planning to install • Imperial (London) (staff shortage) • RAL PP (due to start soon) • Others have expressed interest

  9. T1 experiences • Running production dCache • 25 TB disk • Interfaces to permanent disk • Interfaces to tape (dteam only atm) – no delete yet • SC dCache • 4 disk servers • 13 GridFTP servers • Aggregated 500 MB/s

  10. T1 experiences – dCache • Stability is good  • Performance is good  • Optimising by adding more hardware • Head node, SRM, and SRM db all on different machines for SC2 • Satisfied with support from dCache 

  11. Operational problems, T1 • SRM requests left open • If interrupted, lcg-gt leaves requests open • Users must call lcg-sd to close • Running dCache GridFTP on multihomed host • TURL points to default IP address • Some minor VO related problems • E.g. total available space published, not space per VO

  12. Other storage work • One size doesn’t necessarily fit all… • Investigating DPM (result next week)… • xrootd… (BaBar using it) • Collaborating with CASTOR group • Own SRM implementation • RAL Tapestore plans • Investigating running CASTOR • …or need to upgrade current software

  13. Summary • dCache • currently managing access to storage at Tier 1 • Deployed or deploying to 4-5 major T2 sites • Interfacing to disks and tape at RAL • But tape only opened for dteam right now

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