The EPIKH Project (Exchange Programme to advance e-Infrastructure Know-How) gLite Grid Services Abderrahman El Kharrim Joint EPIKH/EUMEDGRID Support event in Rabat Morocco,

A genuine new concept in distributed computing –Could bring radical changes in the way people do computing –Share the computing power of many countries for your needs –Descentralized the placement of the computing resources Basic concept is simple: –I.Foster : “coordinated resource sharing and problem solving in dynamic, multi-institutional virtual organizations. “ –End-user :  I want to be able to use computing resources as I need  I don’t care who owns resources, or where they are Have to be secure My programs have to run there –NO centralized control of resources or users Grid overview Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

Grid overview If the WEB is able to share information, the Grid is intended to share computing power and storage Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

Members of the grid can dynamically be organized into multiple virtual organizations (VOs) with common purposes. The resources shared among VOs may be data, special hardware, processing capability, Software and licenses. Members of a grid can be part of multiple VOs at the same time. Examples of VOs : eumed, biomed, atlas, … 4 Grid overview - VOs Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

5 Grid overview - The big picture User Interface (UI) Computing Element Storage Element Site X Information System (BDII) submit query retrieve Workload Management Logging & Bookkeeping (WMS) publish state File and Replica Catalogs Authorization Service query update credential publish state discover services (CE) (SE) Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

6 gLite overview Rabat, Joint EPIKH/EUMEDGRID Support Site Admin gLite is a grid middleware providing services that sit between the user applications and the underlying computing and storage resources. The grid middleware services: should –Find convenient places for the application to be run –Optimize the use of the resources –Organize efficient access to data –Deal with security –Run the job and monitor its progress –Recover from problems –Transfer the result back to the user

Computational Resource Physical machines on which users wants to run their programs and to store/access data files Job A computational task (a binary application or script) that a user wants to run on the Grid, and retrieve the results Job Submission It is the action of delegating the application to the Grid middleware for its execution. 7 gLite overview - Terminology Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

8 Workload Management Data Management Security Information & Monitoring Access gLite overview - Services API Computing Element Workload Management Metadata Catalog Storage Element Data Movement File & Replica Catalog Authorization Authentication Information & Monitoring Application Monitoring Auditing Job Provenance Package Manager CLI Accounting Site Proxy Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

Authentication and authorization User Interface Workload Management system Computing Element Worker Node Storage Element LCG File Catalog Information Systems 9 gLite overview - Services/Clients Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

10 Authentication is based on X.509 PKI infrastructure –Certificate Authorities (CA) issue (long lived) certificates identifying individuals  Commonly used in web browsers to authenticate to sites –Trust between CAs and sites is established (offline) –In order to reduce vulnerability, on the Grid user identification is done by using (short lived) proxies of their certificates Proxies can –Be delegated to a service such that it can act on the user’s behalf –Be stored in an external proxy store (MyProxy) –Be renewed (in case they are about to expire) –Include additional attributes Virtual Organization Membership Service (VOMS) is a service that keeps track of the members of a VO. –Support MyProxy (stored proxies). –VOMS Grants users authorization to access the resource at VO level Authentication/Authorization Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

Contains clients: –Job management –Data management –Access to Information System –Authentication Installation in user space (tarball) or rpm based User Interface Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

12 Workload Management System WMS: Resource brokering, workflow management, I/O data management –Web Service interface: WMProxy –Task Queue: keep non matched jobs –Information SuperMarket: optimized cache of information system –Match Maker: assigns jobs to resources according to user requirements Job submission & monitoring Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

o Contains CREAM (Computing Resource Execution And Management) service. o CREAM can be used by a Generic Client: an end-user interacting directly with the Computing Element, or by the Workload Manager, which submits a given job to an appropriate CE found by the matchmaking process. 13 Computing Element Direct Job Submission WMS Submission through the WMS CREAM Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

o Job management through the WMS provides many benefits compared to direct job submission to the CE: –The WMS can manage multiple CEs, and is able to forward jobs to the one which better satisfies a set of requirements, which can be specified as part of the job description. – The WMS can be instructed to handle job failures: if a job aborts due to problems related to the execution host, the WMS can automatically resubmit it to a different CE. – The WMS provides a global job tracking facility using the LB service. – The WMS supports complex job types (job collections, job with dependencies) which can not be handled directly by the CEs. 14 Computing Element Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

15 That’s where the jobs are being run Contains clients –Data management Has mechanism to install/manage VO specific software Installs as tarball or rpm based Worker Node Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

o The Storage Element is the service which allows a user or an application to store data for future retrieval. o To define a storage element, we need to know:  Storage Resource Manager (SMR).  Storage Resource Types.  Transfer Protocol. 16 Storage Element Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

o Storage Resource Manager (SMR):  It is a middleware interface application that makes standard data management operations between SEs of different resource type transparent to user.  These data management operations include:  File transfer.  Space reservation.  Renaming of files.  File directory creation. 17 Storage Element Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

o Storage Resource Types: 1.For relatively small SEs:  Disk-based storage implementation is employed together with disk pool manager, as the SRM. 2.For bigger SEs:  The mass storage system (MSS) is implemented with CASTOR (CERN Advanced STORage Manager) as the SRM. o For hybrids between disk pool storage and MSS, we have dCache as the SRM. o Transfer Protocol:  To transfer of files in and out of the SE.  Globus GridFTP mandatory.  Others if available (https, ftp, etc). 18 Storage Element Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

o LFC = LGC File Catalog o Keeping track of the location of files and organize them in a logical way so that they will be accessible from anywhere. o Resolves logical filenames (LFN) to physical location of files (URL understood by SRM) and storage elements. o The identification of files on the storage elements is done through the use of different identifiers:  Logical File Name (LFN)  Globally Unique Identifier (GUID)  Storage URL (SURL) (or Physical File Name (PFN) )‏  Transport URL (TURL)‏ o while LFNs and GUIDs are used for the identification of files, SURLs and TURLs provide the necessary information to access and retrieve the files 19 LFC File Catalog Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

o What?  System to collect information on the state of resources. o Why?  To discover resources of the grid and their nature.  To check for health status of resources.  To provide data in order to manage the workload more efficiently. o How?  Monitoring and publishing fresh data on the state of resources. o Who?  User searching specific resources for their activity.  Workload Management System.  Other monitoring system 20 Information System Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

o The IS architecture used in gLite is Berkeley Database Information Index (BDII):  Stores information at VO level. o Site GIIS (Grid Index Information Server):  Stores information at site level. o GRIS(Grid Resource Information Server):  Stores information at resource level. 21 Information Systems Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

22 Information Systems Rabat, Joint EPIKH/EUMEDGRID Support Site Admin

Thank you.. 23 Rabat, Joint EPIKH/EUMEDGRID Support Site Admin