Grid-Brick Event Processing Framework in GEPS CHEP 03 – La Jolla, California A. Amorim, P. Trezentos, N. Almeida, H. Fei, L.Pedro, J.Villate, H.Wolters.

Grid-Brick Event Processing Framework in GEPS

CHEP 03 – La Jolla, California

A. Amorim, P. Trezentos, N. Almeida, H. Fei, L.Pedro, J.Villate, H.Wolters

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Outline Introduction Architecture Overview Data Flow How do we do it Action! Vantages and disadvantages On-going and future work Summary

[email protected] FCUL - Lisbon

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Introduction

What is GEPS Grid-based Event Processing System Developed on top of Globus Provides web-based access to grid

computing environment for event processing Developed by GridPT working group


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Introduction

Main Idea

Do NOT move data!

Each node stores and is

reponsible by a subset of the whole data…


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Introduction

The usual way

High speed Disks

Data Center


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Introduction

Our way

User terminal User terminal User terminal………..

Job submit server

Meta-data catalogue


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Architecture Overview

User submits a query through a interface to the Job Submit Server (JSS).

Job submitted information will be stored in the Metadata Catalog.


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The job is submitted to the grid nodes using Globus API functions.

All the nodes query their own information and retrieve a result.

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JSS receives result from the Grid nodes and produces a final one

User can download or consult the final result

User can also visualize the state of the job in each Grid node


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Data-flow

User terminal(PHP interface)

BROKER

Meta-data catalogue


JSS

Grid node

Brick

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How do we do it:

Technologies used Globus PgSQL LDAP PHP ROOT


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How do we do it:

Relevant Features Globus

Toolkit that provide GRID API functions

PgSQL Meta-data catalogue implementation

LDAP Query Grid node information

PHP Web interface


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Action!

The human interface

Main Page

Submit a Job

GREED info

Job status


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Action!

Enabling ROOT Queries The job is submitted to the grid nodes All the nodes query their own information with

ROOT and retrieve a ROOT file with a TTree JSS receives the ROOT files and produces a

final ROOT file with the result of the query User can download or consult the final file

because it is a TTree.


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Action!

Enabling ROOT Queries (cont) Stores the information in each node using TTree’s Filter the information in each node and retrieve a

result file that include a TTree Join all the result files in the Job Submit Server using

a TChain and produces a final TTree that is the query result

View the final result file with a TBrowser or with Carrot


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Action!

Enabling ROOT Queries (reading ROOT files)

Analysis Performance Reading From a TFile

050

100150200250300350400

100 500 1000 2000 4000

Events

Tim

e S

pen

t (s

)

30% Events

60% Events

90% Events


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Action!

Enabling ROOT Queries (reading ROOT files)

Analysis Performance Reading From a TTree

0

20

40

60

80

100

120

140

100 500 1000 2000 4000 6000

Events

Tim

e S

pen

t (s

)

30% Events

60% Events

90% Events


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Action!

Special Features used ROOT

TObject TTree CINT Filtering data from TTree ROOT I/O TChain

Carrot Browsing ROOT files Histograming variables


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Vantages and disavantages

Vantages Commodity Data Storage Huge Scalability (400 GB/node) Granularity

Disadvantages Load balancing

Suitable storage policy Fault tolerance

Data replication or Backup


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On-going and future work

Error handling and fault-tolerance Recover mechanisms for each node Create a redundancy mechanism to recover

from a malfunction in the nodes Develop a storage mechanism to submit more

work to the best nodes Load balancing

Provide to user several interfaces to submit work


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Summary

A different approach is being developed There is already a real prototype working Some (good) results have been achieved A lot of work already done…..

But …. Still a lot of work to do!


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Acknowledgments

Thank you to those who are developing and participating in this project A. Amorim ([email protected]) P. Trezentos ([email protected]) N. Almeida ([email protected]) H. Fei ([email protected]) L.Pedro ([email protected]) J.Villate ([email protected]) H.Wolters ([email protected])

Keep the good workThanks for hearing me!


Grid-Brick Event Processing Framework in GEPS CHEP 03 – La Jolla, California A. Amorim, P. Trezentos, N. Almeida, H. Fei, L.Pedro, J.Villate, H.Wolters.

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