MDS-2.1 and Futures

Karl Czajkowski

Information Sciences InstituteUniversity of Southern California

Talk Outline

Introduction– Problem, history, etc.

MDS-2 Architecture– Protocols– Features, services

MDS-2.1 Software– Technology map

Information Model– Additional background

Resource Discovery/Monitoring

Distributed users and resources Variable resource status Variable grouping and connectivity

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dispersed users

VO-A VO-B

partioned network

Basic Grid Acquisition 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!

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

Base Features

Virtual Organizations (Vos)– Group together resources

– Support community-specific “discovery”

– Specialized “views” Scalability

– Many resources

– Many Vos

– Graceful degradation of service

Virtual Organizations

Collaborating individuals and institutions– Shared goals

– Enable sharing of resources

– Non-locality of participants Dynamic in nature

– VOs come and go

– Resources joing and leave Vos

– Resource change status and fail Community-wide goals

Scalability

Large numbers– Many resources– Many users

Independence– Resources shouldn’t affect one another– Vos shouldn’t affect one another

Graceful degradation of service– “As much function as possible”– Tolerate partitions, prune failures

New MDS-2.1 Features

Security– GSI mutual-authentication

– Fine-grained access control by GSI name Performance

– Better query speeds

– Less stale information Extensibility Convenience

Service Hierarchy

Resource Description via Info. Protocol (GRIP)– Co-located with resource on network

Aggregate Directories (via GRIP or other)– Can be made hierarchical

Dynamic Registration via Reg. Protocol (GRRP)

discovery (GRIP?)

lookup (GRIP)registration (GRRP)

VO-specific AggDirs

standard ResDesc services

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Distributed Services

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

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fault-partitionregistrationmessages

replicated directories divergent directories

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VO-A VO-B

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Soft-state Registration

Periodic notification– Service/resource is available

– Expected-frequency metadata Automatic extension

– Add new resources to directories

– Invite resource to join new directory Self-cleaning

– Reduce occurrence of “dead” references

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 Dir. Access Protocol (LDAP)

– Standard with many client implementations

– Used for GRIP (and GRRP currently)

MDS-2.1 Development Activities

Incorporating external advances– New OpenLDAP 2.0.x code-base

– Cyrus-SASL/GSI security integration

– Leveraging new Globus packaging model Improving internal components

– Better query servicing

– New configuration/policy support

– Invitation (reverse registration)

MDS-2.1 External Software Stack

OpenLDAP 2.0.x (.11)– Implements LDAPv3 protocol– Client and server components

Cyrus-SASL– Generic security– We provide loadable SASL/GSI plugin

Globus GSI (repackaged)– Provides GSS-API interface to PKI– Loadable module works with SASL plugin

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 (or future CAS)– Per-object access rule attributes

MDS-2.1 Internal Software

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)

MDS-2.1alpha GRIS Providers

globus-software reports Globus packages grid-info-host reports host OS info grid-info-host-interfaces reports NICs grid-info-host-load reports host load grid-info-host-filesystem reports disks globus-gram-reporter reports jobs

GRIS Dispatch Tests

Concurrent dispatch for each provider:

1. Could search intersect provider? No, then stop.

2. Is provider cache stale? Yes, then refill.

3. Apply search filter to cache data. Combine all providers’ results

MDS-2.1 GRIS Configurationdn: sw=Globus, hn=${GLOBUS_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’ddn: hn=${GLOBUS_HOSTNAME},{GRID_INFO_ORGANIZ

ATION_DN}

objectclass: GlobusTop

objectclass: GlobusActiveObject

objectclass: GlobusActiveSearch

type: exec

path: /opt/globus-mds/libexec

base: globus-gram-reporter

args: -f /opt/globus-mds/etc/globus-gram-rep

orter.conf -onetime

cachetime: 30

timelimit: 10

sizelimit: 20

…

Hierarchical GIIS

Maintain set of remote services– Track incoming live registrations– GRIS or GIIS registrants

Cached proxy results (now), or– Same cache logic as GRIS– Refill cache with “chaining” queries

LDAPv3 referral results (planned)– Do not maintain any local info cache– Redirect clients to active registrants

Extensible GIIS Framework

Modular registration actions– Re-use registration protocol decoding

– Specialize directory update

– e.g. prefetch indexable data Modular query actions

– Re-use query protocol decoding

– Specialize query handler algorithm

– e.g. utilize precomputed indices

MDS-LDAP Data Model

Info named within service Info tagged with content type name(s) Values associated with typed attributes

valuestypesname

objectclass: computer

system: mips irix

dn: hn=hostX

objectclass: service

dispatchtype: immediate

dn: queue=default, hn=hostX

url: gram://hostname/default

objectclass: queue

dn: perf=load5, hn=hostX

objectclass: perf

objectclass: loadaverage

period: 10

load5: 3.2

dn: store=scratch, hn=hostX

objectclass: storage

objectclass: raidstore

free: 33515 MB

raidmode: stripe

MDS-LDAP Query Model

Search scoping– Search rooted in namespace

– Search depth of “root,” “root’s children,” or “root’s subtree”

Search filter– Value or type comparison

– Logical combinations of filters Namespace represents concept space

Namespace Management

Info is named uniquely within a service Append “source name” to disambiguate

locally, or use URLs to refer to remote info

host host host host

host

host

host: hn=R3host: hn=R2host: hn=R1

host: hn=R2host: hn=R1

host: hn=R1host: hn=R2, O=O2host: hn=R1, O=O2host: hn=R3, O=O1

O1 O2 R1

R2R1R3R2R1

host: hn=R2, O=O1

AggDir

AggDir

AggDir

ResDesc

host: hn=R1, O=O1

More Information

Questions? HPDC-10 Paper (to appear August 2001)

– “Grid Information Services for Distributed Resource Sharing”

MDS-2.1 Alpha Website– http://www.globus.org/mds2-alpha

– Early access to development code