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A conceptual model of grid resources and services

A conceptual model of grid resources and services. Authors: Sergio Andreozzi Massimo Sgaravatto Cristina Vistoli. Presenter: Sergio Andreozzi INFN-CNAF Bologna (Italy) sergio.andreozzi@cnaf.infn.it. OUTLINE. Short introduction to the GLUE activity GLUE Schema overview

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A conceptual model of grid resources and services

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  1. A conceptual model of grid resources and services Authors: Sergio Andreozzi Massimo Sgaravatto Cristina Vistoli Presenter: Sergio Andreozzi INFN-CNAF Bologna (Italy) sergio.andreozzi@cnaf.infn.it

  2. OUTLINE • Short introduction to the GLUE activity • GLUE Schema overview • The conceptual model • The implementation status • Deployment roadmap • Related works • Open issues CHEP 2003 - March, 24 2003

  3. GLUE: WHAT • GLUE: Grid Laboratory Uniform Environment • collaboration effort focusing on interoperability between US and EU HENP Grid middlewares • Targeted at core grid services • Resource Discovery and Monitoring • Authorization and Authentication • Data movement infrastructure • Common software deployment procedures • Preserving coexistence for collective services CHEP 2003 - March, 24 2003

  4. GLUE: WHO and WHEN • Promoted by DataTAG and iVDGL projects • Activity started in April 2002 considering as first step common information service schema between EU and US HENP Grid projects • Important contributions from the following projects: DataGrid, Globus, GriPhyN, PPDG, SRM • Main contributors (in alph order): J.Gordon, C.Kesselman, P.Kunstz, J.McGee, R.Pordes, A.Shoshani, J.Schopf, B.Tierney CHEP 2003 - March, 24 2003

  5. GLUE Schema overview 1/2 • Conceptual model of grid resources to be used by the Grid Information Service for discovery and monitoring purposes • Based on the experience of DataGrid and Globus schema proposals CHEP 2003 - March, 24 2003

  6. GLUE Schema overview 2/2 • Conceptual model – version 1.0 • Finalized in Oct ’02 • Model of computing resources (Ref. CE) • Model of storage resources (Ref. SE) • Model of relationships among them (Ref. Close CE/SE) • Currently working on version 1.1 • Extensions • Model of network resources • Possible other adjustements will come from experience (e.g. DataGrid v.2.0) CHEP 2003 - March, 24 2003

  7. GLUE Computing resources requirements • Separation between services and resources that implement it • Needs for both detailed host info (monitoring issue) and aggregate view (discovery issue) CHEP 2003 - March, 24 2003

  8. GLUE Computing Element • Computing Element: entry point into a queuing system • There is one computing element per queue of a local resource management system • The information associated with a computing element is limited only to information relevant to the queue • All information about the physical resources accessed by a queue is represented by the Cluster information element CHEP 2003 - March, 24 2003

  9. GLUECluster/Subcluster/Host • Cluster: container that groups together subclusters or hosts.  A cluster may be referenced by more than one computing element • Subcluster: collection of “homogeneous” hosts: • All hosts of a subcluster have the same value for the set of asserted attributes   • Host: characterizes the configuration of a computing node (e.g. processor, main memory, software) CHEP 2003 - March, 24 2003

  10. Computing Resources in GLUE Computing Element Computing Element Computing Element subcluster2 subcluster1 Cluster 1 CHEP 2003 - March, 24 2003

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  13. GLUEStorageService/Space/Library • Storage Service: • grid service identified by a URI that manages disk and tape resources in term of Storage Spaces • all hardware details are masked • the Storage Service performs file transfer in or out of its Storage Spaces using a specified set of third part data movement services (e.g. GridFTP) • files are managed with respect to the lifetime policy specified for the Storage Space where they are kept • a specific date and time lifetime policy can be specified for each file and this is applied against a compatibility rules table CHEP 2003 - March, 24 2003

  14. GLUEStorage Service/Space/Library • Storage Space: portion of a logical storage extent identified by: • an association to a directory of the underlying file system (e.g. /permanent/CMS) • a set of policies (MaxFileSize, MinFileSize, MaxData, MaxNumFiles, MaxPinDuration, Quota) • an association to access control base rules CHEP 2003 - March, 24 2003

  15. GLUEStorage Service/Space/Library • Storage Library: the machine providing for both storage space and storage service CHEP 2003 - March, 24 2003

  16. GLUEStorage Service/Space/Library Storage Service protocol info Storage Space Status, Policies, Access Rules Directory Storage Library Architecture type + file system + files CHEP 2003 - March, 24 2003

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  18. Computing/Storage Services relationships in Glue • The problem: • Job executed on Computing Elements (CEs) • Job may access files stored in Storage Space • Several replicas of these files can be spread over the grid • The best replica is CE-dependent • Which strategy to assign the job to a CE and select the best replica for it? • Current solution: • Computing-Storage Services association statically defined by SiteAdmin’s • When the network resource model will be in place, this association could be dynamically defined CHEP 2003 - March, 24 2003

  19. GLUE SchemaImplementation status • Implementation status • For Globus MDS 2.x: • LDAP Schema (DataTAG WP 4.1) • Info providers for both computing and storage resources • For EDG R-GMA: • Relational model implementation (DataGrid, both schema and information providers) • For Globus OGSA: • XML Schema (Globus) CHEP 2003 - March, 24 2003

  20. Deployment roadmap • In DataTAG, a mixed testbed already in place with: • EDG 1.4.x (+ Glue) nodes in Italy • LCG-0 node at CERN • VDT nodes in US (FNAL, Indiana University) • CMS, ATLAS and ALICE experiment suites already successfully integrated with EDG Resource Broker, Glue schema based • Grid middleware distributions and the Glue schema • Already included in • VDT 1.1.7 • LCG-0 • Will be soon included in • EDG 2.0 • Globus 2.2.x CHEP 2003 - March, 24 2003

  21. Related works • EDT-LCG Monitoring collaboration: • development of a Grid monitoring toolin order to monitor the overall functioning of the Grid • Will be presented here at CHEP • Today, parallel session 1b-Monitoring, 4.50 PM • Network resource modeling: • Definition of a network model that enables an efficient and scalable way of representing the communication capabilities between grid services for brokering activity • Will be presented here at CHEP: • next Thursday, parallel session 1b–Monitoring, 4.10 PM CHEP 2003 - March, 24 2003

  22. Main open issues • Computing: • refine aggregated view of a cluster from the queue viewpoint • Storage: • Gain better understanding of Storage Service, when mapping a disk space access or an SRM service • High Level Grid Services, define a general grid service CHEP 2003 - March, 24 2003

  23. REFERENCE • DataTAG Project • http://www.datatag.org • Grid Laboratory Uniform Environment (GLUE) DataTAG WP4 and iVDGL Interoperability Group version 0.1.2 • http://www.hicb.org/glue/glue-v0.1.2.doc • GLUE Schema documents • http://www.cnaf.infn.it/~sergio/datatag/glue • EDT-LCG Monitoring • http://gridmon.na.infn.it/lcg-edt • GGF CIM Grid Schema WG • http://www.isi.edu/~flon/cgs-wg/ CHEP 2003 - March, 24 2003

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