1. Building, Monitoring and Maintaining a Grid Jorge Luis Rodriguez University of Florida jorge@phys.ufl.edu July 11-15, 2005

2. Jorge Luis Rodriguez 2 Grid Summer Workshop 2005, July 11-15 What we’ve already learned –What are grids, why we want them and who is using them: GSW intro & L1… –Grid Authentication and Authorization: L2 –Harnessing CPU cycles with condor: L3 –Data Management and the Grid: L4 In this lecture –Fabric level infrastructure: Grid building blocks –The Open Science Grid Introduction

3. Jorge Luis Rodriguez 3 Grid Summer Workshop 2005, July 11-15 Computational Clusters Storage Devices Networks Grid Resources and Layout: –User Interfaces –Computing Elements –Storage Elements –Monitoring Infrastructure… Grid Building Blocks

4. Jorge Luis Rodriguez 4 Grid Summer Workshop 2005, July 11-15 Dell Cluster at UFlorida’s High Performance Center Computer Clusters Cluster Management “frontend” Tape Backup robots I/O Servers typically RAID fileserver Disk Arrays The bulk are Worker Nodes A few Headnodes, gatekeepers and other service nodes

5. Jorge Luis Rodriguez 5 Grid Summer Workshop 2005, July 11-15 A Typical Cluster Installation Network Switch Pentium III Head Node/Frontend Server Pentium III Worker Nodes WAN  Cluster Management OS Deployment Configuration Many options ROCKS (kickstart) OSCAR (sys imager) Sysconfig  Computing Cycles  Data Storage  Connectivity I/O Node + Storage

6. Jorge Luis Rodriguez 6 Grid Summer Workshop 2005, July 11-15 Networking Internal Networks (LAN) –Private, accessible only to servers inside a facility –Some sites allow outbound connectivity via Network Address Translation –Typical technologies used Ethernet (0.1, 1 & 10 Gbps) HP, Low Latency interconnects –Myrinet: 2, 10 Gps –Infiniband: max at 120Gps External connectivity –Connection to Wide Area Network –Typically achieved via same switching fabric as internal interconnects Network Switch Pentium III Head Node/Frontend Server Pentium III Worker Nodes WAN “one planet one network” Global Crossing I/O Node + Storage

7. Jorge Luis Rodriguez 7 Grid Summer Workshop 2005, July 11-15 The Wide Area Network Ever increasing network capacities are what make grid computing possible, if not inevitable The Global Lambda Integrated Facility for Research and Education (GLIF)

8. Jorge Luis Rodriguez 8 Grid Summer Workshop 2005, July 11-15 Batch scheduling systems –Submit many jobs through a head node #!/bin/sh for each i in $list_o_jobscripts do /usr/local/bin/condor_submit $i done –Execution done on worker nodes Many different batch systems are deployed on the grid –condor (highlighted in lecture 3) –pbs, lsf, sge… Primary means of controlling CPU usage, enforcing allocation policies and scheduling of jobs on the local computing infrastructure Computation on a Clusters Network Switch Pentium III Head Node/Frontend Server Pentium III Worker Nodes WAN I/O Node + Storage

9. Jorge Luis Rodriguez 9 Grid Summer Workshop 2005, July 11-15 Storage Devices Many hardware technologies deployed from: Single fileserver Linux box with lots of disk: RAID 5… Typically used for work space and temporary space a.k.a. “tactical storage” to Large Scale Mass Storage Systems Large peta-scale disk + tape robots systems Ex: FNAL’s Enstore MSS –dCache disk frontend –Powderhorn tape backend Typically used as permanent stores a.k.a “strategic storage” StorageTek Powderhorn Tape Silo

10. Jorge Luis Rodriguez 10 Grid Summer Workshop 2005, July 11-15 Tactical Storage Typical Hardware Components –Servers: Linux, RAID controllers… –Disk Array IDE, SCSI, FC RAID levels 5, 0, 50, 1… Local Access –Volumes mounted across compute cluster nfs, gpfs, afs… –Volume Virtualization dCache pnfs Remote Access –gridftp: globus-url-copy –SRM interface space reservation request scheduling Network Switch Pentium III Head Node/Frontend Server Pentium III Worker Nodes WAN /share/DATA = nfs:/tmp1 /share/TMP = nfs:/tmp2 /share/DATA = nfs:/tmp1 /share/TMP = nfs:/tmp2 /tmp1 /tmp2

11. Jorge Luis Rodriguez 11 Grid Summer Workshop 2005, July 11-15 Layout of Typical Grid Site Computing Fabric Grid Middleware Grid Level Services + + => A Grid Site => VDT OSG Compute Element Storage Element User Interface Authz server Monitoring Element Monitoring Clients Services Data Management Services Grid Operations The GridThe Grid

12. Jorge Luis Rodriguez 12 Grid Summer Workshop 2005 July 11-15 Grid3 and Open Science Grid

13. Jorge Luis Rodriguez 13 Grid Summer Workshop 2005, July 11-15 The Grid3 Project

14. Jorge Luis Rodriguez 14 Grid Summer Workshop 2005, July 11-15 The Grid3 grid A total of 35 sites Over 3500 CPUs Operations Center @ iGOC Began operations Oct. 2003 A total of 35 sites Over 3500 CPUs Operations Center @ iGOC Began operations Oct. 2003

15. Jorge Luis Rodriguez 15 Grid Summer Workshop 2005, July 11-15 Grid3 Metrics CPU usage per VO 03/04 thru 09/04 Data challenges for ATLAS and CMS CPU usage averaged over a day 03/04-9/04 CMS’ DC04 ATLAS’ DC2 Simulation Events 41.4 x 10 6 evts, 11/03-3/05 Grid3 contribution to MC production for CMS USMOP = USCMS S&C + Grid3

16. Jorge Luis Rodriguez 16 Grid Summer Workshop 2005, July 11-15 The Open Science Grid A consortium of Universities and National Laboratories to building a sustainable grid infrastructure for Science in the U.S. …

17. Jorge Luis Rodriguez 17 Grid Summer Workshop 2005, July 11-15 Grid3  Open Science Grid Begin with iterative extension to Grid3 –Shared resources, benefiting broad set of disciplines –Realization of the critical need for operations –More formal organization needed because of scale Build OSG from laboratories, universities, campus grids –Argonne, Fermilab, SLAC, Brookhaven, Berkeley Lab, Jeff. Lab –UW Madison, U Florida, Purdue, Chicago, Caltech, Harvard, etc. Further develop OSG –Partnerships and contributions from other sciences, universities –Incorporation of advanced networking –Focus on general services, operations, end-to-end performance

18. Jorge Luis Rodriguez 18 Grid Summer Workshop 2005, July 11-15 Enterprise Technical Groups Research Grid Projects VOs Researchers Sites Service Providers Universities, Labs activity 1 activity 1 activity 1 Activities Advisory Committee Core OSG Staff (few FTEs, manager) OSG Council (Chair, officers from major stakeholders, PIs, Faculty & Lab managers) Executive Board (8-15 representatives Chair, Officers) OSG Organization

19. Jorge Luis Rodriguez 19 Grid Summer Workshop 2005, July 11-15 OSG Integration Provisioning OSG Activities and Tech. Groups OSG deployment Policy Privilege TG-Policy TG-Monitoring & Information Docs DRM IPB dCache TG-Storage Operations TG-Support Centers MIS Monitoring & Information Systems A Sampling of current OSG TG and Activities

20. Jorge Luis Rodriguez 20 Grid Summer Workshop 2005, July 11-15 OSG Technical Groups & Activities Technical Groups address and coordinate –Propose and carry out activities related to their given areas –Liaise & collaborate with other peer projects (U.S. & international) –Participate in relevant standards organizations. –Chairs participate in Blueprint, Grid Integration and Deployment activities Activities are well-defined, scoped set of tasks contributing to the OSG –Each Activity has deliverables and a plan –… is self-organized and operated –… is overseen & sponsored by one or more Technical Groups

21. Jorge Luis Rodriguez 21 Grid Summer Workshop 2005 July 11-15 OSG Authentication & Authorization “Authz” Privilege

22. Jorge Luis Rodriguez 22 Grid Summer Workshop 2005, July 11-15 Authentication & Authorization Authentication: Verify that you are who you say you are –OSG users typically use the DOEGrids CA –OSG sites also accept CAs from LCG and other organizations Authorization: Allow a particular user to use a particular resource –Legacy Grid3 method, gridmap-files –New Privilege method, employed at primarily at US- LHC sites

23. Jorge Luis Rodriguez 23 Grid Summer Workshop 2005, July 11-15 OSG Authentication: Grid3 Style VOMS server @ iGOC edg-mkgridmap VOMS server @ LLab VOMS server @ OLab user DNs site a client site b client site n client mapping of user’s grid credentials (DN) to local site group account gridmap-file LColab, Lexp1 Oexp1, Aexp2… iVDGL, GADU… DN mappings VOMS= Virtual Organization Management System DN=Distinguished Name edg= European Data Grid (EU grid project)

24. Jorge Luis Rodriguez 24 Grid Summer Workshop 2005, July 11-15 The Privilege Project Application of a Role Based Access Control model for OSG An advanced authorization mechanism

25. Jorge Luis Rodriguez 25 Grid Summer Workshop 2005, July 11-15 The Privilege Project Provides Centralized, dynamic mapping of grid users to local OS qualifiers –VOMSes are still used as grid identities DN db –Gone, however are the static grid-mapfiles Improvement to Access Control policy implementation –The GUMS service –Access rights granted based on user’s VO membership User selected role(s) Grid Identity Unix ID Certificate DN  local user VO Role(s)  local group(s) Grid Identity Unix ID Certificate DN  local user VO Role(s)  local group(s)

26. Jorge Luis Rodriguez 26 Grid Summer Workshop 2005, July 11-15 Server with VDT 1.3 based on GT3.2 Server with VDT1.3 based on gt3.2 Client server (UI) Web-Service Container Privilege Project Components VOMS Server Servers with VDT 1.3 based on gt3.2 Gridmap callout gridFTP & Gate- keeper job-manager PRIMA module 6. instantiates GUMS Identity Mapping Service (manages user accounts on resources, incl. dynamic allocation) 3. Standard globus-job-runrequest with VOMS-extended proxy Client tool for role selection: VOMS-proxy-init 1. VOMS-proxy-init request with specified role 2. Retrieves VO membership and role attribute User Management (VOMSRS) SAML Statement: Decision=Permit, with obligation local UID=xyz, GID=xyz 5. HTTPS/SOAP Response: May user “Markus Lorch” of “VO=USCMS / Role=prod” access this resource? 4. HTTPS/SOAP Request: SAML Query: VO membership synchronization VOMS Attribute Repository An OSG site A VO service

27. Jorge Luis Rodriguez 27 Grid Summer Workshop 2005, July 11-15 Authorization in OSG OSG will support multiple modes of operation Will work with legacy client and/or server combinations –Full legacy server: VOMS+edg-makegridmap Privilege enabled client requests (VOMS-proxy-init) will be mapped to local user as previously: VOMS extensions ignored –Full Privilege server: All Privilege components enabled Legacy client requests are supported but user can not be mapped to a different VO or assume a different role under its own VO Also a Grid3 compatibility mode will be supported –Supports privilege operations but without the globus PRIMA callout and thus can not support the “role” based mapping –The gatekeeper/gridFTP server is operated with legacy Grid3 stack (gtk 2.4 servers…) –Automatically provides reverse maps for Grid3/OSG accounting

28. Jorge Luis Rodriguez 28 Grid Summer Workshop 2005, July 11-15 Server with VDT 1.3 based on GT3.2 Server with VDT1.3 based on gt3.2 Client server (UI) Web-Service Container Grid3 Compatibility mode VOMS Server Legacy Grid3 Servers gridFTP & Gate- keeper job-manager 4. instantiates GUMS Identity Mapping Service (manages user accounts on resources, incl. dynamic allocation) 3. Standard globus-job-runrequest with VOMS-extended proxy Client tool for role selection: VOMS-proxy-init 1. VOMS-proxy-init request 2. Retrieves VO membership and role attribute User Management (VOMSRS) May user “Markus Lorch” of “VO=USCMS / Role=prod” access this resource? The role however, is ignored A. Periodically queries GUMS server VO membership synchronization VOMS Attribute Repository An OSG site with legacy gatekeeper or gridFTP server A VO service grid- mapfile cron job DN mapping to a local UID=xxx, but no role based assignment B. Response create static grid-mapfile reverse map to OSG accounting

29. Jorge Luis Rodriguez 29 Grid Summer Workshop 2005 July 11-15 OSG Grid Monitoring MIS Monitoring & Information Systems MIS Monitoring & Information Systems

30. Jorge Luis Rodriguez 30 Grid Summer Workshop 2005, July 11-15 OSG Monitoring & Information System Grid Level Clients –User interfaces & APIs –Graphical Displays Gridcat MonALISA ACDC job Monitor Metrics DataViewer BDII Site Level infrastructure –Scripts & tools collectors –Databases –Application APIs MonALISA server –MonALISA client –Metrics DataViewer OSG MIS-CI –ACDC job Monitor –GidCat MDS: Generic Info. Provider –BDII

31. Jorge Luis Rodriguez 31 Grid Summer Workshop 2005, July 11-15 Site Level Infrastructure stor_stat Ganglia … GIP job_state Monitoring information DataBase Collector others… MonALISA Discovery Service ACDC GINI, SOAP, WDSL… GRAM: jobman-mis https: Web Services GridCat MonALISA server MIS-Core Infrastructure MDS Monitoring Information Consumer API Historical information DataBase

32. Jorge Luis Rodriguez 32 Grid Summer Workshop 2005, July 11-15 OSG Grid Level Clients Tools provide basic information about OSG resources –Resource catalog: official tally of OSG sites –Resource discovery: what services are available, where are they and how do I access it –Metrics Information: Usage of resources over time Used to asses scheduling priorities –Where and when should I send my jobs? –Where can I put my output? Used to monitor health and status of the Grid

33. Jorge Luis Rodriguez 33 Grid Summer Workshop 2005, July 11-15 GridCat http://osg-cat.grid.iu.edu http://www.ivdgl.org/grid3/gridcat

34. Jorge Luis Rodriguez 34 Grid Summer Workshop 2005, July 11-15 MonALISA

35. Jorge Luis Rodriguez 35 Grid Summer Workshop 2005 July 11-15 OSG Provisioning OSG Software Cache OSG Meta Packager Grid Level Services Provisioning

36. Jorge Luis Rodriguez 36 Grid Summer Workshop 2005, July 11-15 The OSG Software Cache Most software comes from the VDT OSG components include –VDT configuration scripts –Some OSG specific packages too Pacman is the OSG Meta-packager –This is how we deliver the entire cache to resources

37. Jorge Luis Rodriguez 37 Grid Summer Workshop 2005, July 11-15 What is The VDT ? A collection of software –Grid software –Virtual data software –Utilities An easy installation mechanism –Goal: Push a button, everything just works –Two methods: Pacman: installs and configures it all RPM: installs some of the software, but no configuration A support infrastructure –Coordinate bug fixing –Help desk

38. Jorge Luis Rodriguez 38 Grid Summer Workshop 2005, July 11-15 What is in the VDT? Condor Group Condor/Condor-G DAGMan Fault Tolerant Shell ClassAds NeST Globus Alliance (3.2 pre web) Job submission (GRAM) Information service (MDS) Data transfer (GridFTP) Replica Location (RLS) EDG & LCG Make Gridmap Cert. Revocation list updater Glue & Gen. Info. provider VOMS ISI & UC Chimera & Pegasus NCSA MyProxy GSI OpenSSH UberFTP LBL PyGlobus Netlogger DRM Caltech MonALISA jClarens (WSR) VDT VDT System Profiler Configuration software US LHC GUMS PRIMA Others KX509 (U. Mich.) Java SDK (Sun) Apache HTTP/Tomcat MySQL Optional packages Globus-Core {build} Globus job-manager(s) Condor Group Condor/Condor-G DAGMan Fault Tolerant Shell ClassAds NeST Globus Alliance (3.2 pre web) Job submission (GRAM) Information service (MDS) Data transfer (GridFTP) Replica Location (RLS) EDG & LCG Make Gridmap Cert. Revocation list updater Glue & Gen. Info. provider VOMS ISI & UC Chimera & Pegasus NCSA MyProxy GSI OpenSSH UberFTP LBL PyGlobus Netlogger DRM Caltech MonALISA jClarens (WSR) VDT VDT System Profiler Configuration software US LHC GUMS PRIMA Others KX509 (U. Mich.) Java SDK (Sun) Apache HTTP/Tomcat MySQL Optional packages Globus-Core {build} Globus job-manager(s) Core software User Interface Computing Element Storage Element Authz System Monitoring System

39. Jorge Luis Rodriguez 39 Grid Summer Workshop 2005, July 11-15 Pacman Pacman is: –A software environment installer (or Meta-Packager) –A a language for defining software environments –An interpreter that allowing creation, installation, configuration, update, verification and repair such environments Pacman makes installation of all types of software easy LCG/Scram ATLAS/CMT Globus/GPT Nordugrid/RPM LIGO/tar/make D0/UPS-UPD CMS DPE/tar/make NPACI/TeraGrid/tar/make OpenSource/tar/make Commercial/tar/make % pacman –get iVDGL:Grid3 Enables us to easily and coherently combine and manage software from arbitrary sources. ATLAS NPACI D-Zero iVDGL UCHEP VDT CMS/DPE LIGO Enables remote experts to define installation config updating for everyone at once.

40. Jorge Luis Rodriguez 40 Grid Summer Workshop 2005, July 11-15 Pacman Installation 1.Download Pacman –http://physics.bu.edu/~youssef/pacman/ 2.Install the “package” –cd –pacman -get OSG:OSG_CE_0.2.1 –ls condor/ globus/ post-install/ setup.sh edg/ gpt/ replica/ vdt/ ftsh/ perl/ setup.csh vdt-install.log /monalisa...

41. Jorge Luis Rodriguez 41 Grid Summer Workshop 2005, July 11-15 Grid Level Services OSG Grid level Monitoring infrastructure –Mon. & Info. System(s) top level database –Monitoring Authz: mis user OSG Operations infrastructure –Websites, Ops page, web servers … –Trouble ticket system OSG top level Replica Location Service

42. Jorge Luis Rodriguez 42 Grid Summer Workshop 2005 July 11-15 OSG Operations Operations

43. Jorge Luis Rodriguez 43 Grid Summer Workshop 2005, July 11-15 Grid Operations Monitoring Grid status –Use of Grid monitors and verification routines Report, route and track problems and resolution –Trouble ticket system Repository of resource contact information Do this as part of a National distributed system Monitoring and Maintaining the Health of the Grid User support Application support VO issues

44. Jorge Luis Rodriguez 44 Grid Summer Workshop 2005, July 11-15 Operations Model in OSG

45. Jorge Luis Rodriguez 45 Grid Summer Workshop 2005, July 11-15 Ticket Routing in OSG 1 2 3 4 5 6 7 8 9 10 11 12 OSG infrastructure SC private infrastructure User in VO1 notices problem at RP3, notifies their SC (1). SC-C opens ticket (2) and assigns to SC-F. SC-F gets automatic notice (3) and contacts RP3 (4). Admin at RP3 fixes and replies to SC-F (5). SC-F notes resolution in ticket (6). SC-C gets automatic notice of update to ticket (7). SC-C notifies user of resolution (8). User confirms resolution (9). SC-C closes ticket (10). SC-F gets automatic notice of closure (11). SC-F notifies RP3 of closure (12).

46. Jorge Luis Rodriguez 46 Grid Summer Workshop 2005 July 11-15 OSG Integration and Development Integration

47. Jorge Luis Rodriguez 47 Grid Summer Workshop 2005, July 11-15 Path for New Services in OSG OSG Deployment Activity Metrics & Certification Application validation VO Application Software Installation OSG Integration Activity Release Description Middleware Interoperability Software & packaging Functionality & Scalability Tests Readiness plan adopted Service deployment OSG Operations-Provisioning Activity Release Candidate Readiness plan Effort Resources feedback

48. Jorge Luis Rodriguez 48 Grid Summer Workshop 2005, July 11-15 OSG Integration Testbed Layout Stable Production Release Integration Release Resources enter and leave as necessary OSG Integration Testbed Service platform applications, test harness, clients VO contributed

49. Jorge Luis Rodriguez 49 Grid Summer Workshop 2005, July 11-15 OSG Integration Testbed

50. Jorge Luis Rodriguez 50 Grid Summer Workshop 2005 July 11-15 OSG Further Work Managed Storage Grid Scheduling More

51. Jorge Luis Rodriguez 51 Grid Summer Workshop 2005, July 11-15 Managing Storage Problems: –No real way to control the movement of files into and out of site Data is staged by fork processes! Anyone with access to the site can submit such a request –There is also no space allocation control A grid user can dump files of any size on a resource If users do not cleanup sys admin have to intervene These can easily overwhelm a resource

52. Jorge Luis Rodriguez 52 Grid Summer Workshop 2005, July 11-15 Managing Storage A Solution: SRM ( Storage Resource Manager ) Grid enabled interface to put data on a site –Provides scheduling of data transfer requests –Provides reservation of storage space Technologies in the OSG pipeline –dCache/SRM (disk cache with SRM) Provided by DESY & FNAL SE(s) available to OSG as a service from the USCMS VO –DRM (Disk Resource Manager) Provided by LBL Can be added on top of a normal UNIX file system DRM dCache TG-Storage $> globus-url-copy srm://ufdcache.phys.ufl.edu/cms/foo.rfz \ gsiftp://cit.caltech.edu/data/bar.rfz

53. Jorge Luis Rodriguez 53 Grid Summer Workshop 2005, July 11-15 Grid Scheduling The problem: With job submission this still happens! OSG Site B OSG Site A User Interface VDT Client ? OSG Site X Why do I have to do this by hand? @?>#^%$@#

54. Jorge Luis Rodriguez 54 Grid Summer Workshop 2005, July 11-15 Grid Scheduling Possible Solutions –Sphinx (GriPhyN, UF) Work flow based dynamic planning (late binding) Policy based scheduling More details ask Laukik –Pegasus (GriPhyN, ISI/UC) DAGman based planner and Grid scheduling (early binding) More details in Work Flow lecture 6 –Resource Broker (LCG) Match maker based Grid scheduling Employed by application running on LCG Grid resources

55. Jorge Luis Rodriguez 55 Grid Summer Workshop 2005, July 11-15 Much Much More is Needed Continue the hardening of middleware and other software components Continue the process of federating with other Grids –TeraGrid –LHC/EGEE Continue to synchronize the Monitoring and Information Service Infrastructure Improve documentation TG- Interoperability

56. Jorge Luis Rodriguez 56 Grid Summer Workshop 2005 July 11-15 Summary and Conclusions

57. Jorge Luis Rodriguez 57 Grid Summer Workshop 2005, July 11-15 Conclude with a simple example 1.Log on to a User Interface; 2.Get your grid proxy “logon to the grid” grid-proxy-init 3.Check OSG MIS clients To get list of available sites: depends on your VO affiliation To discover site specific information needed by your job ie, Available services: hostname, port numbers Tactical storage location: $app, $data, $tmp, $wntmp 4.Install your application bins at selected sites 5.Submit your jobs to selected sites via condor-G 6.Check OSG MIS clients to see if jobs have completed 7.Do something like this: If [ 0 ] then echo “Have a coffee (beer, margarita…)” else echo “its going to be a long night” fi

58. Jorge Luis Rodriguez 58 Grid Summer Workshop 2005, July 11-15 OSG Ribbon Cutting OSG Opens for Business on July 20 th, 2005 All Some OSG-Integration Testbed Grandfathered Grid3

59. Jorge Luis Rodriguez 59 Grid Summer Workshop 2005 July 11-15 Conclusion Lots of progress since 1999 But a lot of work still remains! http://www.opensciencegrid.org http://www.griphyn.org http://www.ivdgl.org http://www.ppdg.org

60. Jorge Luis Rodriguez 60 Grid Summer Workshop 2005 July 11-15 The End

61. Jorge Luis Rodriguez 61 Grid Summer Workshop 2005, July 11-15 Grid3 and the Open Science Grid –Grid3: A Shared Grid Infrastructure for Scientific Applications Introduction The Grid3 Grid Grid Metrics –The Open Science Grid The OSG Consortium OSG organization OSG Technical Groups and Activities –OSG Provisioning (Provision Activity) Packaging Software Components: The VDT Grid level services –OSG Grid Level Monitoring (MIS Technical Group) Monitoring infrastructure GridCat MonALISA MDS: Glue and the GIP ACDC –OSG Operations (Support Centers Technical Group) Operations Model Operations Operation in Grid3 –OSG Development and Integration (Integration Activity) The OSG integration testbed The OSG development cycle –OSG Current State OSG Grid Schedule What is still missing –Grid scheduling –Managed Storage –Refinment of the middleware stack … Other Large Scale Grids –The LCG –TeraGrid Summary and Conclusion