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

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

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 March,

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 March,

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 March,

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 March,

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 March,

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 March,

9. 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,

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

11. CHEP March,

12. CHEP March,

13. GLUE Storage Service/Space/Library
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,

14. 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,

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

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

17. CHEP March,

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,

19. GLUE Schema 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,

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 March,

21. 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,

22. Main open issues Computing: Storage:
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,

23. REFERENCE DataTAG Project
Grid Laboratory Uniform Environment (GLUE) DataTAG WP4 and iVDGL Interoperability Group version 0.1.2
GLUE Schema documents
EDT-LCG Monitoring
GGF CIM Grid Schema WG
CHEP March,