MDS2'1 Overview

1
MDS-2.1 Overview

• Jennifer Schopf
• Argonne National Lab
• Northwestern University

2
Introduction

• Problem, history, etc.
• MDS-2 Architecture
• Protocols
• Features, services
• MDS-2.1 Software
• Technology map
• Additional background

3
Resource Discovery/Monitoring

• Distributed users and resources
• Variable resource status
• Variable grouping and connectivity

4
Basic Grid Question Phases

• Resource Discovery
• What resources are relevant?
• Bootstraps planner state
• Resource Status Query
• How do resources compare (now)?
• Refines planner knowledge
• Resource Control
• Did I acquire the resources?
• Not an information service task!

5
MDS History

• MDS-1 (classic)
• Centralized database
• Globus 1.1.2 and earlier
• Did not scale
• MDS-2
• Distributed services
• MDS 2.0 in Globus 1.1.3
• New MDS 2.1 development in alpha release
• MDS 2.1.a1 April 30, 2001
• MDS 2.1a2 May 30, 2001

6
MDS-2 Base Features

• Virtual organizations (VOs)
• Group together resources
• Support community-specific discovery
• Specialized views
• Scalability
• Many resources
• Many VOs
• Graceful degradation

7
Virtual Organizations

• Collaborations between individuals and
  institutions
• Shared goals
• Enable sharing of resources
• Non-locality
• Dynamic in nature
• VOs come and go
• Resources join and leave
• Resources change status and fail
• Community Wide Goals

8
Scalability

• Large numbers
• Many resources
• Many users
• Independence
• Resources shouldn't affect one another
• VOs shouldn't affect one another
• Graceful degradation
• As much function as possible
• Tolerate partitions, prune failures

9
New MDS 2.1 features

• Security
• GSI authentication
• Access control on information
• Performance
• Better query speeds
• Less stale information
• Extensibility
• Convenience

10
MDS 2 Architecture
VO Specific Agg Dirs
D
D
Discovery (GRIP)
Registration (GRRP)
Lookup (GRIP)
R
R
R
R
Standard Rsc desc serv.

• Resource Description via Information
  Protocol(GRIP)
• Co-located with resource on network
• Aggregate Directories (via GRIP or other)
• Can be made hierarchical
• Dynamic Registration via Registration protocol
  (GRRP)

11
Distributed Services

• Service scales with Grid growth
• Loose consistency model tolerates failures
• Interoperability by protocols

12
Soft-state Registration

• Periodic notification
• Service/resource is available
• Granularity metadata
• Automatic extension
• Add new resources to directories
• Invite resource to join new directory
• Self-cleaning
• Reduce occurrence of dead references

13
MDS-2 Implementation

• Grid Resource Information Service (GRIS)
• Provides resource description
• Modular content gateway
• Grid Index Information Service (GIIS)
• Provides aggregate directory
• Hierarchical groups of resources
• Lightweight Directory Access Protocol (LDAP)
• Standard with many client implementations
• Used for GRIP (and GRRP currently)

14
MDS-2.1 Development Activities

• Incorporating external advances
• New OpenLDAP 2.0.x code-base
• Cyrus-SASL/GSI security integration
• Leveraging new Globus packaging
• Improving internal components
• Better query servicing
• New configuration/policy support
• Invitation (reverse registration)

15
MDS-2.1 External Software Stack

• OpenLDAP 2.0.x
• Implements LDAPv3 protocol
• Client and server components
• Cyrus-SASL
• Generic security
• We use loadable GSS-API interface
• Globus GSI (repackaged)
• Provides GSS-API interface to GSI
• Loadable module works with SASL code

16
MDS-2.1 Internal Software Stack

• Wrappers/tools
• Simplify typical idioms
• Modular GRIS providers
• Probe/query resource status
• Generates LDIF-format data
• LDAP server backend modules
• GRIS provider dispatch/caching
• GIIS implementation(s)

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Stock MDS-2.1 GRIS Providers

• globus-version reports Globus software
• grid-info-host reports host OS info
• grid-info-host-interfaces reports host NICs
• grid-info-host-load reports host CPU status
• grid-info-host-filesystem reports host disk
  status
• globus-gram-reporter reports Globus job status

18
GRIS Dispatch Tests

• Simple dispatch for each provider
• 1. Could search intersect provider? No, then
  done.
• 2. Is provider cache stale? Yes, then refill.
• 3. Apply search filter to cache data.
• Combine all provider results

19
Hierarchical GIIS

• Maintain set of remote services
• 1) Track incoming live registrations
• 2) GRIS or GIIS registrants
• Cached proxy results, or
• 1) Same cache logic as GRIS
• 2) Refill cache with chaining queries
• LDAPv3 referral results (planned)
• 1) Do not maintain any local info cache
• 2) Redirect clients to remote registrants

20
Extensible GIIS Framework

• Modular registration actions
• 1) Re-use registration protocol decoding
• 2) Specialize directory update
• 3) e.g. prefetch indexed data
• Modular query actions
• 1) Re-use query protocol decoding
• 2) Specialize query handling
• 3) e.g. utilize precomputed indices

21
More Information

• HPDC 2001 Paper (to appear) Grid Information
  Services for Distributed Resource Sharing
• MDS-2.1 Alpha Website
• http//www.globus.org/mds2-alpha
•  

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The Globus Toolkit Solution MDS-2

• Registration enquiry protocols, information
  models, query languages
• Provides standard interfaces to sensors
• Supports different directory structures
  supporting various discovery/access strategies

24
GIS Architecture
Customized Aggregate Directories
Users
A
A
Enquiry Protocol
Registration Protocol
R
R
R
R
Standard Resource Description Services
25
MDS-2.1 GRIS Configuration

• dn swGlobus, hnGLOBUS_HOSTNAME,
  GRID_INFO_
• ORGANIZATION_DN
• objectclass GlobusTop
• objectclass GlobusActiveObject
• objectclass GlobusActiveSearch
• type exec
• path /opt/globus-mds/bin
• base globus-version
• args -ldif
• cachetime 950400
• timelimit 10
• sizelimit 1
• GRIS Configuration cont'd
•  
• \ldots
•  
• \beginverbatim
• dn hnGLOBUS_HOSTNAME, GRID_INFO_ORGANIZATIO
  N_DN
• objectclass GlobusTop

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MDS 2.1 Security

• PKI authentication
• Static authorization
• class, attribute, object name rules
• Self authorization
• semi-dynamic rule
• requires owner attribute on objects
• Dynamic authorization
• directory-based group lists
• per-object access rule attributes