Globus Overview

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Globus Overview

• CS-780-3 Lecture Notes
• In courtesy of Andy Kowalski

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Overview

• What Defines a Grid
• Globus
• GT1, GT2 (pre OGSA)
• GT3 (post OGSA)
• Issues

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What Defines a Grid?

• We will probably see the spread of computer
  utilities, which, like present electric and
  telephone utilities, will service individual
  homes and offices across the country
• -Len Kleinrock. 1969 1

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What Defines a Grid?

• A computational grid is a hardware and software
  infrastructure that provides dependable,
  consistent, pervasive, and inexpensive access to
  high-end computational capabilities.
• - Ian Foster and Carl Kesselman, 1998 2

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Ian Fosters Three Point Checklist (2002)

• A Grid is a system that
• coordinates resources that are not subject to
  centralized control 2
• using standard, open, general-purpose protocols
  and interfaces 2
• to deliver nontrivial quantities of service 2

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Globus Project

• Multi-institutional research effort on the
  technology required to build a grid or grids
• Mathematics and Computer Science Division at
  Argonne National Laboratory
• Information Sciences Institution at the
  University of Southern California
• University of Chicago
• University of Edinburgh
• Center for Parallel Computers
• Principle Investigators
• Ian Foster - Argonne National Laboratory and
  University of Chicago
• Carl Kesselman - University of Southern California

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Globus Project

• Seek to understand application requirements for a
  usable grid and
• Conduct research and development to create the
  technologies required to build a grid
• Globus toolkit

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Globus Toolkit

• Bag of services
• Developers can use these to build grid
  applications
• Makes use of existing standards when possible
• Interfaces and implementations
• Distinguishes between local and global services
• Defines interfaces to manage heterogeneity
• Does not hide heterogeneity
• Information service to deal with constant changes
• Utilization, failures, new resources, etc.

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Hourglass Principle

• A layered architecture with and hourglass shape
• Grid services should provide a simple
  well-defined interface between applications and
  local services

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GRAM

• Globus Resource Allocation Manager
• Provides a single interface for requesting and
  using remote system resources for executing jobs
• Each GRAM is responsible for the resource
  management systems local to it
• LSF (Load Sharing Facility), Condor, PBS
• Provides a standard interface to these different
  systems
• Applications can access these different systems
  using a standard API
• Within GRAM resource requests are described by
  the Resource Specification Language (RSL)

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GRAM
Broker
RSL
Application
Information Service
Queries Info
Ground RSL
Co-allocator
Single Ground RSL

• Ground RSL is an expanded description of the
  applications request. It may represent more
  than on job.
• Single Ground RSL is a description of a singe
  job created from the Ground RSL. There may be
  more than one created from the original Ground
  RSL.

GRAM
GRAM
LSF
PBS
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RSL

• Resource Specification Language
• Provides a common language to describe resources
• Uses attribute, value pairs
• A simple example
• (executable a.out ( lt-- that is an unquoted
  literal ))
• (directory /home/nobody )
• (arguments arg1 "arg 2")
• (count 1)

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Nexus

• Low-level communications API that supports other
  communication libraries
• Can select alternative low-level protocols based
  on network topology
• Message passing, IP, shared memory
• Can introduce encryption based on source and
  destination of a message
• Intended for use by compiler writers and library
  developers
• CC, HPC, and MPICH-G

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MDS

• Metacomputing Directory Service (GT1)
• Monitoring and Discovery Service (GT23)
• Provides information about the systems in the
  grid
• CPU type, memory, OS, network, etc.
• Queue information, utilization, etc
• Basically a local LDAP server
• MDS ties all the LDAP servers together so
  everyone has access to the same information
• Has an API for discovering, publishing, and
  accessing information

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MDS Architechture

• Grid Index Information Service (GIIS)
• Provides an aggregate directory of lower level
  data
• Grid Resource Information Service (GRIS)
• Runs on a resource and acts like a content
  gateway to the resource
• Information Provider (IP)
• Interface to data collection services

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GSI

• Globus Security Infrastructure
• Deals only with authentication
• Users and services
• Uses x.509 certificates
• Also used username and password (rlogin)
• Uses Secure Socket Layer (SSL) for the connection
  and authentication
• No longer true with GT3
• All Globus services use GSI to authenticate users

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GSI

• Use proxy certificates for non-interactive work
• Jobs executing on remote systems
• Proxy certificates have a limited life time

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CAS

• Community Authorization Service
• In the CAS model, resource providers grant access
  to blocks of resources to a community as a whole,
  and the community uses a CAS server to perform
  fine-grained access control on those resources.
• Resource providers grant course-grained access to
  communities.
• Communities run CAS servers, which keep track of
  fine-grained access control information and grant
  restricted proxies to community members.
• The result is that a CAS user gets the
  intersection of the rights granted by resource
  provider to the community and the rights granted
  by the community to that user.

Slide Taken From 6
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A Typical CAS Request

1. CAS request, authenticated with

CAS Server




CAS-maintained community policy database
User credential
What rights does the community grant to this
user?

• CAS reply, including
• restricted proxy cred

Community subject name
Policy restrictions

User

Resource Server

3. Resource request, authenticated with CAS proxy

Is this request authorized for the community?
Local policy information

Community subject name

Policy restrictions


4. Resource reply

Do the proxy restrictions authorize this request?

Slide Taken From 6
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HBM

• Heartbeat Monitor
• API to register with the service and collect data
• Service expects updates from clients that have
  registered
• If no update is received, attempts to determine
  if the service itself is down or if there are
  other factors

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GASS

• Global Access to Secondary Storage
• Allows programs to use the standard C I/O library
  to read and write files on remote computers
• Reads
• File is copied locally and then read
• Writes
• File is written locally and then copied to their
  destination
• Appends
• Communicated to the remote file as soon as it is
  written

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GEM

• Globus Executable Management
• Support identification, location, and creation of
  executables in heterogeneous environments
• Pre-stages executables to multiple remote sites
• Removes them after execution

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GridFTP

• Secure data transfer protocol
• GSI authentication
• Optimized for high-bandwidh wide-area networks
• Parallel streams - multiple data channels
• Partial file transfer
• Third-party transfers
• Server to server

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Globus Toolkit 3

• Based on the Open Grid Services Architecture
  (OGSA)
• Attempts to leverage industry standards
• Makes use of web services
• Preserves backward compatibility with GT2
• Future releases will begin eliminating
  compatibility
• Client interfaces to services are now WSDL/OGSI
  based

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Issues

• Protocols and interfaces
• Where the GT1 and GT2 implementation of a grid
  service was inadequate for certain grids, others
  would developed competing services using
  different interfaces and protocols
• Defeated the goal of compatibility
• OGSA/OGSI and web services are hoped to resolve
  this
• Dont need the whole thing
• Want to use GSI, need to install all of Globus
• COGs helped eliminate this burden
• Use only what you need

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Issues

• Globus originally seemed focused on compute grids
• Other groups were building data grids
• data grids represent a larger customer base
• GridFTP was over extended
• Was once proposed that it be used for more than
  file transfers
• Message passing
• VO Management

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A few of the Grid Projects with strong HEP
collaboration
Many national, regional Grid projects
-- GridPP(UK), INFN-grid(I), NorduGrid, Dutch
Grid,
European projects
US projects
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The Large Hadron Collider Project 4 detectors
CMS
ATLAS
Storage Raw recording rate 0.1 1
GBytes/sec Accumulating at 5-8
PetaBytes/year 10 PetaBytes of
disk Processing 200,000 of todays fastest
PCs
LHCb
Slide Taken From 8
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Multi-Tiered View of LHC Computing
2.5-10Gbs
2.5-10Gbs
1-10Gbs
Slide Taken From 8
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Jlab Work

• Storage Resource Manager (SRM)
• Collaboration with LBL and FNAL
• Standard interface to a mass storage system
• Jasmine, Enstore, HPSS
• Uses
• GSI for authentication
• Web Services (before OGSA)

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Jlab Work

• Replica Catalog
• Web Services (before OGSA)
• Does not use GSI
• Mysql database used to store the map
• GFN -gt SURL1 SURLN
• Only one server/service
• May deploy mirrors of the database and proxies
• User Job Description Language (uJDL)
• Collaboration with BNL
• High level description of a physics job

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Jlab Work

• Job Scheduling Project
• Accepts a job description from a user
• Creates on or more jobs for execution
• If required, moves all necessary data to the site
  where execution will take place
• Moves output files to specified site, location
• Will use the uJDL but need to also define a
  System Job Description Language
• Lower level description of a compute job

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Job Scheduler Design
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Current Replica Catalog
Site A
Site B
3
2
1
4
5
6
8
7
Site C
Site D
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Proposed Replica Catalog Project
Site A
Site B
2
3
4
1
5
6
7
P2P Overlay Network
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10
9
Site C
Site D
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Another Replica Catalog Problem

• Given
• Multiple VOs want to share data files
• Each VO represents a country or geographic area
• Each VO will maintain their own Replica Catalog
• Problem
• All VOs that want to participate need seamless
  access to all Replica Catalogs
• Individual VOs need to be able to come and go as
  they please

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Another Replica Catalog Problem
USA
Canada
P2P Overlay Network
Europe
Japan
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References

• 1 Ian Foster. What is the Grid? A Three Point
  Checklist. July 20, 2002.
• 2 Ian Foster and Carl Kesselman, editiors. The
  Grid Blueprint for a New Computing
  Infrastructure. 1998.
• 3 Ian Foster and Carl Kesselman. The Globus
  Project A Status Report. Proceedings of
  IPPS/SPDP98 Heterogeneous Computing Workshop.
  1998.
• 4 Ian Foster and Carl Kesselman. Globus
  Ametacomputing Infrastructure Toolkit.
  International Journal of Supercomputer
  Applications. 1997
• 5 Globus Project. Globus Toolkit 2.2 MDS
  Technology Brief. January 30, 2003.
• 6 Globus Project. Community Authorization
  Service (CAS) Overview. December 18, 2001.
• 7 Ian Foster. Open Grid Services Architecture.
  Plenary Talk at CHEP 2003. March 26, 2003.
• 8 Ian Bird. Deploying the LHC Computing Grid.
  Plenary Talk at CHEP 2003. March 26, 2003.