A conceptual model of grid resources and services Authors: Sergio Andreozzi Massimo Sgaravatto Cristina Vistoli Presenter: Sergio Andreozzi INFN-CNAF Bologna (Italy)

CHEP March, OUTLINE Short introduction to the GLUE activity GLUE Schema overview – The conceptual model – The implementation status – Deployment roadmap Related works Open issues

CHEP March, 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 March, 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 March, 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 March, 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 March, 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 March, 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 March, GLUE Cluster/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 March, Computing Resources in GLUE Computin g Element Computin g Element Computin g Element Computin g Element Computin g Element Computin g Element subcluster2 subcluster1 Cluster 1

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13 GLUE Storage Service/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 March, GLUE Storage 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 March, GLUE Storage Service/Space/Library Storage Library: the machine providing for both storage space and storage service

CHEP March, GLUE Storage Service/Space/Library Storage Library Architecture type + file system + files Storage Service protocol info Storage Space Status, Policies, Access Rules Directory

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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 March, GLUE Schema Implementation 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 March, 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 – LCG-0 Will be soon included in – EDG 2.0 – Globus 2.2.x

CHEP March, Related works EDT-LCG Monitoring collaboration: – development of a Grid monitoring tool in 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 March, 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 March, REFERENCE DataTAG Project – Grid Laboratory Uniform Environment (GLUE) DataTAG WP4 and iVDGL Interoperability Group version – GLUE Schema documents – EDT-LCG Monitoring – GGF CIM Grid Schema WG –