Chapter 7:-

The anatomy of the Grid

Prepared By:- NITIN PANDYA

Assistant Professor

SVBIT.

Content

Problem statement

Architecture

Globus Toolkit

Futures

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The Grid Problem

Resource sharing & coordinated problem solving in dynamic,

multi-institutional virtual organizations

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Elements of the Problem

Resource sharing

Computers, storage, sensors, networks, …

Sharing always conditional: issues of trust, policy, negotiation,

payment, …

Coordinated problem solving

Beyond client-server: distributed data analysis, computation,

collaboration, …

Dynamic, multi-institutional virtual orgs

Community overlays on classic org structures

Large or small, static or dynamic

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Grid Communities & Applications: Data Grids

for High Energy Physics

Tier2 Centre ~1 TIPS

Online System

Offline Processor Farm

~20 TIPS

CERN Computer Centre

FermiLab ~4 TIPS France Regional Centre

Italy Regional Centre

Germany Regional Centre

Institute Institute Institute Institute ~0.25TIPS

Physicist workstations

~100 MBytes/sec

~100 MBytes/sec

~622 Mbits/sec

~1 MBytes/sec

There is a “bunch crossing” every 25 nsecs.

There are 100 “triggers” per second

Each triggered event is ~1 MByte in size

Physicists work on analysis “channels”.

Each institute will have ~10 physicists working on one or more channels; data for these channels should be cached by the institute server

Physics data cache

~PBytes/sec

~622 Mbits/sec or Air Freight (deprecated)

Tier2 Centre ~1 TIPS

Tier2 Centre ~1 TIPS

Tier2 Centre ~1 TIPS

Caltech ~1 TIPS

~622 Mbits/sec

Tier 0

Tier 1

Tier 2

Tier 4

1 TIPS is approximately 25,000

SpecInt95 equivalents

Image courtesy Harvey Newman, Caltech 5 NITIN PANDYA

Grid Communities and Applications: Network

for Earthquake Eng. Simulation

NEESgrid: national infrastructure to

couple earthquake engineers with

experimental facilities, databases,

computers, & each other

On-demand access to experiments,

data streams, computing, archives,

collaboration

NEESgrid: Argonne, Michigan, NCSA, UIUC, USC 6 NITIN PANDYA

Grid Communities and Applications:

Mathematicians Solve NUG30

Community=an informal

collaboration of mathematicians and

computer scientists

Condor-G delivers 3.46E8 CPU

seconds in 7 days (peak 1009

processors) in U.S. and Italy (8 sites)

Solves NUG30 quadratic assignment

problem 14,5,28,24,1,3,16,15,

10,9,21,2,4,29,25,22,

13,26,17,30,6,20,19,

8,18,7,27,12,11,23

MetaNEOS: Argonne, Iowa, Northwestern, Wisconsin 7 NITIN PANDYA

Community =

1000s of home computer

users

Philanthropic computing

vendor (Entropia)

Research group (Scripps)

Common goal= advance

AIDS research

Grid Communities and Applications: Home

Computers Evaluate AIDS Drugs

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Grid Architecture

Why Discuss Architecture?

Descriptive

Provide a common vocabulary for use when describing Grid

systems

Guidance

Identify key areas in which services are required

Prescriptive

Define standard “Intergrid” protocols and APIs to facilitate

creation of interoperable Grid systems and portable applications

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What Sorts of Standards?

Need for interoperability when different groups want to share resources

E.g., IP lets me talk to your computer, but how do we establish & maintain sharing?

How do I discover, authenticate, authorize, describe what I want to do, etc., etc.?

Need for shared infrastructure services to avoid repeated development, installation, e.g.

One port/service for remote access to computing, not one per tool/application

X.509 enables sharing of Certificate Authorities

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So, in Defining Grid Architecture, We Must

Address …

Development of Grid protocols & services

Protocol-mediated access to remote resources

New services: e.g., resource brokering

“On the Grid” = speak Intergrid protocols

Mostly (extensions to) existing protocols

Development of Grid APIs & SDKs

Facilitate application development by supplying higher-level abstractions

The (hugely successful) model is the Internet

The Grid is not a distributed OS!

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The Role of Grid Services and Tools

Remote

monitor

Remote

access

Information

services

Fault

detection . . . Resource

mgmt

Collaboration

Tools

Data Mgmt

Tools

Distributed

simulation . . .

net

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Layered Grid Architecture

Application

Fabric “Controlling things locally”: Access to, & control

of, resources

Connectivity “Talking to things”: communication (Internet

protocols) & security

Resource “Sharing single resources”: negotiating access,

controlling use

Collective

“Coordinating multiple resources”: ubiquitous

infrastructure services, app-specific distributed

services

Internet

Transport

Application

Link

Internet Protocol A

rchitecture

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Protocols, Services, and Interfaces Occur

at Each Level

Languages/Frameworks

Fabric Layer

Applications

Local Access APIs and Protocols

Collective Service APIs and SDKs

Collective Services Collective Service Protocols

Resource APIs and SDKs

Resource Services Resource Service Protocols

Connectivity APIs

Connectivity Protocols

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Where Are We With Architecture?

No “official” standards exist

Nor is it clear what this would mean

But:

Globus Toolkit has emerged as the de facto standard for several

important Connectivity, Resource, and Collective protocols

GGF has an architecture working group

Technical specifications are being developed for architecture

elements: e.g., security, data, resource management, information

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The Globus Toolkit

Grid Services Architecture (1): Fabric Layer

Just what you would expect: the diverse mix of resources that

may be shared

Individual computers, Condor pools, file systems, archives,

metadata catalogs, networks, sensors, etc., etc.

Few constraints on low-level technology: connectivity and

resource level protocols form the “neck in the hourglass”

Globus toolkit provides a few selected components (e.g.,

bandwidth broker)

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Grid Services Architecture (2): Connectivity

Layer Protocols & Services

Communication

Internet protocols: IP, DNS, routing, etc.

Security: Grid Security Infrastructure (GSI)

Uniform authentication & authorization mechanisms in multi-

institutional setting

Single sign-on, delegation, identity mapping

Public key technology, SSL, X.509, GSS-API

Supporting infrastructure: Certificate Authorities, key management,

etc.

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User

User Proxy

Globus

Credential

Site 1

Kerberos

GRAM Process

Process

Process GSI

Ticket

Site 2

Public Key

GRAM

GSI

Certificate

Process

Process

Process

Authenticated

interprocess

communication

CREDENTIAL

Mutual

user-resource

authentication

Mapping

to

local ids

Assignment of

credentials to

“user proxies”

Single sign-on via “grid-id”

Authorization

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GSI Futures

Scalability in numbers of users & resources

Credential management

Online credential repositories (“MyProxy”)

Account management

Authorization

Policy languages

Community authorization

Protection against compromised resources

Restricted delegation, smartcards

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GSI Futures: Community Authorization

2. CAS reply, with and resource CA info

user/group membership

resource/collective membership

collective policy information

CAS

Does the

collective policy

authorize this

request for this

user?

User

1. CAS request, with resource names and operations

Resource

Is this request

authorized for

the CAS?

Is this request

authorized by

the

capability? local policy information

3. Resource request, authenticated with

capability

4. Resource reply

capability

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Grid Services Architecture (3): Resource Layer

Protocols & Services

Resource management: GRAM

Remote allocation, reservation, monitoring, control of [compute] resources

Data access: GridFTP

High-performance data access & transport

Information: MDS (GRRP, GRIP)

Access to structure & state information

& others emerging: catalog access, code repository access, accounting, …

All integrated with GSI

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GRAM Resource Management Protocol

Grid Resource Allocation & Management

Allocation, monitoring, control of computations

Simple HTTP-based RPC

Job request:

Returns a “job contact”: Opaque string that can be passed between clients, for

access to job

Job cancel, Job status, Job signal

Event notification (callbacks) for state changes

Pending, active, done, failed, suspended

Servers for most schedulers; C and Java APIs

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Resource Management Futures

GRAM-2 protocol (ETA late 2001)

Advance reservations & multiple resource types

Recoverable requests, timeout, etc.

Use of SOAP (RPC using HTTP + XML)

Policy evaluation points for restricted proxies

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Data Access & Transfer

GridFTP: extended version of popular FTP protocol for Grid

data access and transfer

Secure, efficient, reliable, flexible, extensible, parallel,

concurrent, e.g.:

Third-party data transfers, partial file transfers

Parallelism, striping (e.g., on PVFS)

Reliable, recoverable data transfers

Reference implementations

Existing clients and servers: wuftpd, nicftp

Flexible, extensible libraries

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Grid Services Architecture (4): Collective

Layer Protocols & Services

Index servers aka metadirectory services

Custom views on dynamic resource collections assembled by a community

Resource brokers (e.g., Condor Matchmaker)

Resource discovery and allocation

Replica management and replica selection

Optimize aggregate data access performance

Co-reservation and co-allocation services

End-to-end performance

Etc., etc.

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The Grid Information Problem

Large numbers of distributed “sensors” with different properties

Need for different “views” of this information, depending on

community membership, security constraints, intended purpose,

sensor type

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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 29 NITIN PANDYA

GRAM GRAM GRAM

LSF Condor NQE

Application

RSL

Simple ground RSL

Information

Service

Local

resource

managers

RSL

specialization Broker

Ground RSL

Co-allocator

Queries

& Info

Resource Management Architecture

* See talk by Jarek Nabrzyski et al.

ASCI DISCOM

Condor-G

Nimrod-G

Poznan*

U. Lecce

DUROC

MPICH-G2

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Data Grid Architecture

Metadata Catalog Replica Catalog

Tape Library

Disk Cache

Attribute

Specification

Logical Collection and Logical

File Name

Disk Array Disk Cache

Application

Replica

Selection

Multiple Locations

NWS

Selected

Replica

GridFTP commands Performance

Information &

Predictions

Replica Location 1 Replica Location 2 Replica Location 3

MDS

+ “Virtual data”: transparency wrt location and materialization

(www.griphyn.org) 31 NITIN PANDYA

Grid Futures

Large Grid Projects are in Place DOE ASCI DISCOM

DOE Particle Physics Data Grid

DOE Earth Systems Grid

DOE Science Grid

DOE Fusion Collaboratory

European Data Grid

Egrid (see talk by G. Allen et al.)

NASA Information Power Grid

NSF National Technology Grid

NSF Network for Earthquake Eng Simulation

NSF Grid Application Development Software

NSF Grid Physics Network 33 NITIN PANDYA

Problem Evolution Past-present: O(102) high-end systems; Mb/s networks; centralized

(or entirely local) control

I-WAY (1995): 17 sites, week-long; 155 Mb/s

GUSTO (1998): 80 sites, long-term experiment

NASA IPG, NSF NTG: O(10) sites, production

Present: O(104-106) data systems, computers; Gb/s networks; scaling, decentralized control

Scalable resource discovery; restricted delegation; community policy; GriPhyN Data Grid: 100s of sites, O(104) computers; complex policies

Future: O(106-109) data, sensors, computers; Tb/s networks; highly flexible policy, control

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The Future: All Software is Network-Centric

We don’t build or buy “computers” anymore, we borrow or

lease required resources

When I walk into a room, need to solve a problem, need to

communicate

A “computer” is a dynamically, often collaboratively

constructed collection of processors, data sources, sensors,

networks

Similar observations apply for software

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And Thus …

Reduced barriers to access mean that we do much more

computing, and more interesting computing, than today =>

Many more components (& services); massive parallelism

All resources are owned by others => Sharing (for fun or

profit) is fundamental; trust, policy, negotiation, payment

All computing is performed on unfamiliar systems =>

Dynamic behaviors, discovery, adaptivity, failure

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Summary

The Grid problem: Resource sharing & coordinated problem

solving in dynamic, multi-institutional virtual organizations

Grid architecture: Emphasize protocol and service definition to

enable interoperability and resource sharing

Globus Toolkit as a source of protocol and API definitions, reference

implementations

For more info: www.globus.org, www.griphyn.org,

www.gridforum.org

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