1. J Jensen / WP5 /RAL UCL 4/5 March 2004 GridPP / DataGrid wrap-up Mass Storage Management J Jensen j.jensen@rl.ac.uk

2. WP5 Mass Storage Management - n° 2 Objectives u Develop Uniform interface to mass storage u Interface with Replica Management u Users shouldn’t need to know what the storage system is u Publish information

3. WP5 Mass Storage Management - n° 3 Objectives – uniform interface u Control interface n Developed own interface, later deployed as web service n Now moving toward SRM 1 for int’l compatibility u Data Transfer interface n Globus GridFTP required u Information interface n Publish to MDS – then to R-GMA via GIN

4. WP5 Mass Storage Management - n° 4 Achievements – Storage Element u Flexible architecture n Cope with changing requirements n Pluggable features such as access control n Easy to extend u Security n Secure interfaces n File level access control (not in EDG 2.1 though) u Currently supports CASTOR, HPSS, ADS, as well as disk = SE “Classic” = Not in EDG 2.1 += EDG SE Information Producers GridFTP RFIO NFS SRM Core SE Core Mass Storage Interfaces Data Transfer InformationControl

5. WP5 Mass Storage Management - n° 5 Storage Element team u Most developments done by 3-4 people at RAL n O Synge, R Tam, G Johnson, T Shah, J Jensen – code (>) n J Gordon, J Jensen – WP mgmt u Contributions from Manchester n A McNab et al – GSI, GACL, pool accounts u Contributions from Liverpool n M George, A Washbrook – testing, ACL handling u Contributions from Edinburgh n A Earl – testing, metadata stuff u Other contributions n ADS team at RAL n WP2, WP3,…

6. WP5 Mass Storage Management - n° 6 Storage Element u SE’s performance is acceptable n Performance dominated by data transfer times s E.g. 0.7 second per file for small files via GridFTP n Performance dominated by mass storage access s 10 minutes to stage in file from ADS s 30 minutes to stage in file from CASTOR n Basic core performance – 0.3 seconds per command

7. WP5 Mass Storage Management - n° 7 Storage Element u Scalability n Scalability an issue, particularly for EO with many small files n Release 2.1 : 10000 files ok, 10000000 files not n Limits reached in underlying file system n Being addressed in new metadata implementation u Install and configure n Manual n LCFG-ng n Difficult with heterogonous storage interface machines

8. WP5 Mass Storage Management - n° 8 Achievements – SE deployment EDG SEs as of 17 Feb 2004 Note Taiwan ! Data from R-GMA (WP3) and mapcenter (WP7) Many sites have more than one SE – a few sites have only Classic SE London alone has three sites: IC, UCL, QMUL

9. WP5 Mass Storage Management - n° 9 Int’l Collaborations n SRM s Collaboration between Fermilab, Jefferson Lab, Lawrence Berkeley, RAL, CERN s Contributed to the design of the SRM version 2 protocol n GLUE s Contributed to the design of GLUE storage schema n GGF s Tracked developments in appropriate working groups s SRM not currently part of GGF – may be from ‘10 n Dissemination s Talks at conferences and in working groups, publications,…

10. WP5 Mass Storage Management - n° 10 Achievements beyond release 2.1 u Access Control Lists (ACL) n Based on GACL n Fine-grained: Access based on user, file, and operation n Files can share ACLs n Work required to make more usable and user- friendly

11. WP5 Mass Storage Management - n° 11 Lessons learned u Choice of architecture was definitely right n Architecture has successfully coped with changing requirements u Look for opportunities for component reuse n Used web services deployment and security components provided by WP2 n Deployed and developed further information producers supplied by WP3 n Almost all parts of the Data Transfer components developed externally

12. WP5 Mass Storage Management - n° 12 Lessons learned u Prototype implementations live longer than expected n SE’s metadata system was implemented as prototype n Scalability issues discovered on application testbed

13. WP5 Mass Storage Management - n° 13 Lessons learned u Inter-WP integration requires a lot of effort ! n At times, nearly 100% of WP5 devoted to ITeam work and site installation support n Storage interface machines are heterogeneous s More installation support was required u Need to agree standard protocols n Standards must be open and well-defined

14. WP5 Mass Storage Management - n° 14 Exploitation u Used in final EU review middleware demo to access mass storage u Used successfully on EDG testbeds by all EDG applications WPs u The SE provides the Grid interface to ADS at RAL n This is important because ADS is being used by a large variety of scientific applications groups n To be used on LCG testbed Really Soon Now™

15. WP5 Mass Storage Management - n° 15 Exploitation u “Atlas Data Challenge 1.5” n SE is currently used by Atlas to transfer data between ADS at RAL and CASTOR at CERN n About 1500 files; 2 TB in total n Files are copied by EDG RM and registered in an RC at NIKHEF n This work is being done by Atlas outside the EDG testbeds n Keep running into problems: s UKHEP root expiry s SEs at CERN being “recycled” by ARDA s Limits found in parallel transfer in GridFTP