Grid Information Services

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Grid Information Services

• Muhammad Rafi

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Agenda

• What is a Grid?
• Grid Information Services (GIS)
• Services of GIS
• Architectural Choices
• Flat vs. Hierarchical
• Comparison with MDS-1 and MDS-2
• Suggested Architecture
• Conclusion

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What is a GRID?

• Grid
• involves sharing heterogeneous resources (based
  on different platforms, hardware/software
  architectures, and computer languages),
• located in different places belonging to
  different administrative domains over a network
  using open standards.
• In short, it involves virtualizing computing
  resources.

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Definition GRID

• The definitive definition of a Grid is provided
  by Ian Foster in his article "What is the Grid? A
  Three Point Checklist"2 The three points of
  this checklist are
• Computing resources are not administered
  centrally.
• Open standards are used.
• Non-trivial quality of service is achieved

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GRID Information services

• Almost every Grid component relies on some
  external information
• Information provides every Grid element
• Distributed producers
• Distributed Use
• Classical separation
• Grid Information services
• Grid Monitoring services

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Grid Information Services

• Goal
• Seamless integration with diverse and
  heterogeneous resources so as to realize Grid
  computing
• Configuration and adaptation in heterogeneous,
  dynamic environments
• Maintain metadata related with resources
  efficiently
• Information Hardware, software, and status of
  the system
• Operation Add, Delete, Update, Search
• Main functions
• Resource discovery
• Resource monitoring
• Resource lookup

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GIS Requirements

• Requirements
• Scalability
• Scalable, efficient access to dynamic data
• Performance
• Access to static and dynamic information
• Access to multiple information sources
• Robustness
• Decentralized maintenance
• Uniformity
• Uniform, flexible access to information
• Security
• Access control

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General infrastructure

• Services
• Resource information service
• Uniform means of querying resources for their
  current configuration, capabilities, and status
• Answer queries about a particular resource by
  directing the query to an information provider
• Grid Resource Information Service(GRIS) in
  Metacomputing Directory Service(MDS)
• Aggregate directory service
• Means of combining arbitrary GRIS services to
  provide aggregate view that can be explored or
  searched
• Provide the collective-level searching function
• Grid Index Information Service(GIIS) in MDS
• Protocols
• Enquiry(GRIP) and registration(GRRP) protocol

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Service architecture
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MDS

• High performance distributed computing requires
  selection, configuration
• To make good decisions, timely, accurate
  information is invaluable
• Currently, have nonstandard ways to store/access
  the right kind of data
• The Metacomputing Directory Service (MDS) hopes
  to provide a scalable service to handle this need

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MDS

• Grid information service in Globus toolkitTM
• LDAP based information service infrastructure
• Use OpenLDAP software(http//www.openldap.org)
• Currently, version 2.1
• Components
• Data representation and API
• Defined by LDAP v3.0
• Information model
• Schema definition
• Implementation
• Performance, multiple data sources, and
  scalability

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Design Consideration MDS

• Performance
• Scalability and cost
• Uniformity
• Expressiveness
• Extensibility
• Multiple Information Sources
• Dynamic data
• Flexible access
• Security
• Deployability
• Decentralized maintenance

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Current Approach MDS

• Uname, sysinfo
• Simple Network Management Protocol(SNMP),
  NIS(Network Information Service)
• PVM(Parallel Virtual Machine), MPICH (Message
  Passing Interface)
• DNS (Domain Name Service)
• X.500, LDAP (Lightweight Directory Access
  Protocol)
• Chose to integrate existing systems as much as
  possible
• But use LDAP to organize

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Design of MDS

• Representation and Data Access
• Data Model
• Implementation

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Representation of MDS

• Borrows straight from LDAP
• Entry instance of person, network, computer,
  etc.
• Type is created by associating an object class
• Directory Information Tree (DIT)
• hierarchical, tree-structured name space
• Distinguished Name (DN)
• path from leaf to root entry
• lthn dark.mcs.anl.gov ou MCS, o Argonne
  National Laboratory, o Globus, c US gt

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DIT Example
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Object Classes

• LDAP has set of standard class definitions, which
  can be extended (top, group classes, etc.)
• Defines attributes for an entry, and what values
  those attributes may contain
• Attributes may be required or optional
• Can use inheritance to build new classes

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Data Model - MDS

• Consists of DIT hierarchy and object class
  definitions
• Computer centric, not network centric
• People, hosts, communication networks under
  organization

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Data Model- MDS

• GlobusHost
• GlobusNetwork
• Link protocol (ATM, Ethernet)
• Network topology (bus, ring)
• Physical media (copper, fiber)
• GlobusNetworkInterface
• Physical characteristics (speed) and hardware
  address
• Hosts contain network interfaces
• Network interfaces attached to networks

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Configuration Example
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MDS- Representation
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Data Model

• Physical vs. Logical Network info
• Single network, multiple protocol stacks
• Each may have distinct interface and performance
• Images multiple logical views of the same
  physical network (RFC 1609)
• contains new information, and pointer back to
  physical
• Physical has reference to all images that point
  to it
• GlobusHostImage
• GlobusNetworkImage
• GlobustNetworkInterfaceImage

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Implementation

• While LDAP interface met most needs, default
  implementation was somewhat slow
• Problems
• Single information provider
• Client/server architecture
• Scope of Data
• Allows info providers to provide information per
  attribute
• Time to Live (TTL) for attribute (before
  refreshing)
• Update scope process, computation, global

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Simple Queries

• What are the network interfaces for ATM?
• Find GlobusNetworkInterface-gtGlobusNetwork
  (link_protocolATM)
• For that GNI, GlobusNetworkInterface-gtGlobusNetwor
  kInterfaceImage (ip_address)
• Which nodes can use vendor protocols on fast
  internal networks?
• Two GlobusHostImages belong to the same
  GlobusNetworkImage object

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MDS- Recap
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MDS with Globus

• Nexus communication module
• Uses MDS to find out what low-level mechanisms
  are between modules
• Select between mechanism, based on rules
• Rules based on dynamic information or programmer
  preference
• Code runs unchanged, but can adapt to meet
  performance needs
• I-WAY TestBed (heterogeneous virtual machines)
• Resource Location
• Resource Brokers

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Future MDS

• Use in GUSTO
• Extend Globus components to use MDS
• Expand information sources
• Optimize for common operations
• Sophisticated applications (e.g. resource
  scheduling)
• Performance metrics

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Conclusion

• Designed to provide dynamic information in a
  timely, scalable manner
• Take advantage of LDAP flexibility and growing
  usage in industry
• Provide information richness in extensible manner