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gLite Information System(s)

Learn about gLite Information Systems, GLUE Schema, and LCG Information System including Grid elements, R-GMA, server architecture, and more. Understand the hierarchy, LDAP model, and Consumer-Producer model.

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gLite Information System(s)

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  1. gLite Information System(s) Antonio Fuentes Bermejo Antonio.fuentes@rediris.es http://www.rediris.es

  2. Outline • Grid Information Systems Overview • gLite Information Systems • GLUE Schema • Grid elements • LCG Information System • Hierarchy • LDAP model • R-GMA • Overview • Server Architecture • Consumer-Producer model • User interfaces • RGMA Concepts • References

  3. Grid Information Systems Overview • Collect information of grid resources • Discovering new added resources • Monitoring load and health status • Publish these information • Periodically updated • Well know data model • Used by • Users searching a concrete resource • WMS allocating and managing jobs • Other monitoring services

  4. gLite Information Systems • Basic data model. • Grid Laboratory Uniform Environment (GLUE) Schema. • Two architectures in glite3 • LCG Information System • BDII over Globus MDS. • OpenLDAP interface. • Preserves LCG-2 compatibility. • Relational Grid Monitoring Architecture (R-GMA) • Based on the GMA standard from the Grid Global Forum • Information in SQL relational databases • Web Services. • Future replacement of LCG IS.

  5. GLUE Schema

  6. GLUE Schema • A schema of objects and attributes describing Grid resources and its relationships. • Originally a EU-DataTAG and US-iVDGL coordinated effort. • Current participants: EGEE, OSG, Globus and NorduGrid. • A way to describe Grid info • Statically and dynamically supplied • Hierarchically represented • Independently of the framework (LDAP, XML, SQL…) • Actual release (1.2) is mapped into • LDAP • XML • Old ClassAd (used by Condor Matchmaking)

  7. Site Element

  8. Cluster Element

  9. Computing Element

  10. LCG Information System

  11. LCG Information System Levels • Resource level: Grid Resource Information Server (GRIS) • One GRIS on top of each CE, SE, RB, MyProxy (no WNs). • Sensors and scripts get status of concrete resources statically (e.g. GlueCEUniqueID) or dynamically (e.g. GlueCEStateWaitingJobs) • Site level: Grid Index Information Server (GIIS) • Compiles all the information of the different GRISes in a site. • LCG-2 recommends using a BDII instead of a GIIS • Improves robustness and stability. • Called the site BDII.

  12. LCG Information System Levels • Top level: Berkeley DB Information Index (BDII) • Keeps all Grid information about the VOs (generally only one). • Stores information from local BDIIs or GIISes in its database. • Only queries sites that are included in a configuration file.

  13. LCG Information System Hierarchy

  14. A LDAP Model • Way of collecting info • Pull model (higher level servers periodically query lower level servers) • All servers are based on LDAP • Inherit hierarchical structure (tree-like) • LDAP Data Information Format (LDIF) • Users get info with • Generic applications • ldapsearch (MDS: 2135 and BDII:2170 ports) • Graphical (BDII web; LDAP GUIs) • Always can get information about specific resources (maybe more up-to-date) by querying directly the site BDIIs, GIISes or GRISes. • Querying VO info with lcg-infosites or lcg-info

  15. LDAP Browser showing BDII Info

  16. Relational Grid Monitoring Architecture R-GMA

  17. R-GMA Overview • Added from EDG Project • Based on the GMA standard from the GGF • Information in SQL relational databases (a DB per VO) • Query syntax is a SQL subset • Simple consumer-producer model • Web Services oriented • CLI and Web user interface • Allows self-logging applications • Future replacement of LCG IS

  18. RGMA Overview • R-GMA offers a global view of the VO information • In one large relational DB: virtual database. • Registry stores localization tuples (database rows) published by producers: • Standard Tables: CE state in GLUE Schema (by R-GMA-GIN) • Applications specific tables (e.g. self-logging with Log4j) • Access by SQL queries through a WS interface. • Always updated • Consumers get information directly from the resource • Can be cached by a secondary producer from single o multiple producers to improve access.

  19. R-GMA Server Architecture

  20. R-GMA Server Description • R-GMA Servers • Server (one or several) • Schema Server (There is one common global schema server for the grid) • Registry Server (one or several) • Browser (shows grid information via web browser)

  21. R-GMA Server Description • R-GMA Clients • Generic Client (generic set of APIs for different languages and CLIs) • Servicetool (used by all services to publish its existence and status) • Site Publisher • Client to publish the existence of a site. • Each site must have one R-GMA site publisher. • GadgetIN (GIN) • Client to extract information from MDS and to republish it to R-GMA. • used by the CE. • Data archiver (flexible archiver) • Client to make the data that is coming from the R-GMA site-publisher, servicetool and GIN constantly available. • By default the GLUE tables and service tables are archived, however this can be configured.

  22. R-GMA Servers Per Node Type • The gLite R-GMA Server should deployed the first as part of a gLite grid, because all services require it to publish service information.

  23. R-GMA Producer- Consumer model Registry • The Producer stores its location (URL) in the Registry. • The Consumer looks up producer URLs in the Registry. • The Consumer contacts the Producer to get all the data. • Data passes directly from the producer to the consumer: (does not through the registry) • The user or any user application does not need to know the registry; this will be handled directly by the consumers and producers. Store Location Look up Location Producer Consumer Execute or Stream data

  24. Multiple Producers • The Consumer will get all the URLs that could satisfy the query. • The Consumer will connect to all the Producers. • Producers that can satisfy the query will send the tuples to the Consumer. • The Consumer will merge these tuples to form one result set. Registry Producer 1 Producer 2 Consumer

  25. Select * from CPULoad

  26. Joins SELECT Service.URI Service.emailContact FROM Service S, ServiceStatus SS WHERE (S.URI= SS.URI and SS.up=‘n’)

  27. R-GMA Concepts • Producers • Primary producer • The producer creates and stores locally the informatiion • Secondary producer • The producer stores locally the information coming from primary producers • On Demand • The producer returns the information only under the request of the consumer • Consumer • ContinuousAs soon as new data becomes available it is broadcast to all interested parties • LatestCorresponds to the intuitive idea of “current information” • History • Returns time sequenced data • LATEST RETENTION PERIOD(LRP)and HISTORY RETENTION PERIOD(HRP) • Allow producers to periodically purge old tuples, and to give a precise meaning to the “current state”.

  28. R-GMA user interfaces • R-GMA CLI • Web interface

  29. References • GLUE Schema • http://glueschema.forge.cnaf.infn.it/ • LCG-2 User Guide • https://edms.cern.ch/file/454439//LCG-2-UserGuide.html • gLite 3.0 User Guide • https://edms.cern.ch/file/722398/1.1/gLite-3-UserGuide.pdf • R-GMA home page • http://www.r-gma.org/ • R-GMA in EGEE • http://hepunx.rl.ac.uk/egee/jra1-uk/

  30. Questions…

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