Objective
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Objective. What is RFT ? How does it work Architecture of RFT RFT and OGSA Issues Demo Questions. What is Reliability. The ability of a system or component to perform its required functions under stated conditions for a specified period of time. (IEEE)

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Objective

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Objective

Objective

  • What is RFT ?

  • How does it work

  • Architecture of RFT

  • RFT and OGSA

  • Issues

  • Demo

  • Questions


What is reliability

What is Reliability

  • The ability of a system or component to perform its required functions under stated conditions for a specified period of time. (IEEE)

  • What is Reliability in the context of File Transfer (What is the scope of the problem )

  • How much of it we want to address ?

  • Reliability can mean different things to different people

  • Hash out something that is most general and acceptable to wide range of applications.


Our goal

Our Goal

  • To design and implement a Service that allows byte streams to be transferred in a Reliable manner

  • Reliability,in our context, means that problems of less than a certain,user defined magnitude are dealt with automatically.

  • Build prototypes using different technologies.

    • Java

    • Web Services

    • Etc..


Our goal cont

Our Goal (cont..)

  • A non user based service

    • GridFTP already provides restart markers for recovery but however the client needs to be active.

    • Loss of client requires a manual restart from scratch

  • Store transfer state persistently

  • Recover from a set of Failure conditions reliably


Failure conditions

Failure Conditions

  • List of Failure conditions we want to address

    • Network Failures like dropped connections

    • Machine crashes

    • Temporary Network outages

    • Failure of File Systems

    • Etc…


Interface

Interface

  • submitTransfer()

    • Set of URLs

    • File size for partial file transfers

  • getStatus()

  • cancelTransfer()

  • resumeTransfer()


State diagram

State Diagram


Architecture

Architecture


Ogsa and rft

OGSA and RFT

  • How does RFT fit in OGSA?

  • Things that are different from SC Demo

  • RFT is a Web Service

  • Single Transfer Reliability

  • Service Definition in WSDL

  • Talks XML over SOAP just like any standard Web Service


Rft web service interface

RFT Web Service Interface

  • submitTransferJob()

    • Intput message:fromURL and toURL (strings)

    • Output message: transferJobID (integer)

  • commitTransferJob()

    • Input message: transferJobID

    • Output message: transferJobID

  • getStatus()

    • Input message: transferJobID

    • Output message: status (integer)

  • getStatistics()

    • Input message: transferJobId

    • Output message: Statistics ( complex type)


Our experience

Our Experience

  • SC2001 Demo

  • List of Tests

    • Longest – 3 days transferring 0.3 Terabytes of data from ANL to NERSC

  • Failures recovered from

    • NFS Failures

    • Network outages

    • Server crashes


Issues

Issues

  • Language

    • Prototypes are in Java

    • Language issue should not matter since it is a service whose interface is a socket

  • Persistence Mechanism

    • We used PostGreSQL as database to store the transfer state

    • Can we use File based persistence mechanism

  • Scalability

    • Multiple instances of RFT which may appear as a single logical entity

    • Request redirection ?


Issues cont

Issues (cont..)

  • XRM Functionality

    • Reservations for disk and bandwidth

  • Higher Level Services

    • Interaction between RFT and Higher level Services like Reliable Replication Service

    • Scheduler ??

    • Services like NWS that can give performance estimates

  • ComputeJob Submission

    • File transfer as a Job ?


Issues cont1

Issues(cont..)

  • Security

    • CAS

    • Proxy renewal

  • Error Propagation


Objective

DEMO

  • SC2001 Demo

  • OGSA and RFT


More info

More Info

  • http://www.mcs.anl.gov/~madduri/RFT.html


Questions

Questions ??


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