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									Globus Toolkit

 Massimo Sgaravatto
    INFN Padova
   Grid Services: LHC regional centres
    need distributed computing
   Analyze toolkits that integrate
    distributed computational resources:
       Globus
       Legion
       Globe
       ….

                 Massimo Sgaravatto
   Basic research on GRID problems
   Globus Toolkit
      “Bag of services” for developing

       GRID tools and applications
      Available for most Unix platforms

      Limited functionalities for Win32

                     Massimo Sgaravatto
Globus Architecture

 GlobusView            High-level Services and         Testbed Status

 DUROC              MPI   MPI-IO
                                 Tools CC++   Nimrod/G     globusrun

                                Core Services
  Nexus             Metacomputing                                            GRAM
                      Directory                           Heartbeat
  Gloperf              Service                             Monitor           GASS

Condor        MPI                      Local                          TCP           UDP

 LSF        Easy          NQE
                                      Services              AIX       Irix          Solaris

                                     Massimo Sgaravatto
Core Services
   Security (GSI)
   Information Service (MDS)
   Resource Management (GRAM)
   Remote Data Access (GASS)
   Communication (Nexus)
   Network Performance Monitor (GLOPERF)
   Fault detection (HBM)
   Executable Management (GEM) (???)
                 Massimo Sgaravatto
Globus Security Infrastructure
   Main focus: authentication
       single authentication
            not necessary to manage authentication on
             each GRID node
       Mapping between GRID user-id and local
   Digital signature mechanisms

                        Massimo Sgaravatto
Metacomputing Directory Service
   Static and dynamic information about GRID
    components (host architecture, memory, load,
    network bandwidth, latency. ...)
       Possibility to define new attributes
   Information updated by:
       Globus services (i.e. GRAM Reporter)
       Users/Applications
       Other “providers” (i.e. SNMP)
   Tools and API for discovering, publishing, and
    accessing information
   Standard protocol and interface: LDAP
       Single MDS server (located in USA)
                         Massimo Sgaravatto
Resource Management
   Management of computational resources
   GRAM (Globus Resource Allocation Manager)
    responsible for a set of “local” resources
   Single interface to different resource managers
    (Condor, LSF, NQE, fork, ...)
   Resource Specification Language (RSL) for defining:
       resource requirements (machine type, memory, ...)
       job definition (executable, parameters, ...)
        I.e.: & (ResourceManagementContact =
                  condor”) (count=100) (executable=myapp)

                         Massimo Sgaravatto
Globus Resource Manager Architecture
                   Resource and (High level RSL expression)
                 Job specification

                                                     RSL specialization
 MDS       discovery       Broker
                                                   Create jobs
                                             (Ground RSL expressions)

        GRAM               GRAM                        GRAM

        CONDOR               LSF                         fork

                                        Site2                       Site3

                              Massimo Sgaravatto
Remote Data Access
   GASS (Global Access to Secondary Storage)
   Supported servers: GASS, HTTP, FTP
   Uniform naming using URL:
       I.e.: x-gass://
   Possibility to access remote data sets (distributed
    file system)
       Necessary to modify source code:
            open()  globus_gass_open()
            close()  globus_gass_close()
       Caching
   Possibility to move files from/to remote data
    storage systems
                          Massimo Sgaravatto
Other core services
   Nexus
       Unicast and multicast low level communication library
       Supports different programming models (message
        passing, RPC, etc…)
   HBM (Heartbeat Monitor)
       Monitors the status of registered processes
   GLOPERF (Globus Network Performance
    Measurement Tool)
       Measures throughput and latency between node pairs

                        Massimo Sgaravatto
Evaluation of the Globus Toolkit
   5 sites Testbed (Bologna, CNAF, LNL, Padova,
   Use case: HLT CMS studies
       MC Prod.  Complete HLT chain
   Services
       Resource management
            fork()  Interface to different local resource managers (Condor, LSF)
            Resources chosen by hand  Broker to implement a Global resource
       Data Mover
            to stage executable and input files
            to retrieve output files

                                Massimo Sgaravatto
Use Case: CMS HLT studies

          Massimo Sgaravatto
   Globus installed on 5 Linux PCs in 3 sites
   GSI
       Seems working
   MDS
       Lots of problems, maybe temporary?
   GRAM, GASS, Gloperf, HBM
     Work in progress

                   Massimo Sgaravatto
Other problems
   Documentation not well organized
   Collaboration with HPC Lab, University
    of Lecce is very useful !

                 Massimo Sgaravatto

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