Introduction to EXPReS - SURFnet and JIVE GigaPort seminar for astronomers T.

Transcript Introduction to EXPReS - SURFnet and JIVE GigaPort seminar for astronomers T.

Introduction to EXPReS - SURFnet and JIVE GigaPort seminar for astronomers T. Charles Yun Program Manager EXPReS Project, JIVE

Introduction to VLBI

A one slide VLBI primer

• A radio telescope looks at an object in the sky and collects data to create an “image” of the source • Multiple telescopes can view the same object. The distance between the telescopes is the baseline. The baseline can be compared to building a single telescope with the diameter of this distance (sort of).

• Correlation is the process by which data from multiple telescopes is collected and processed to create a more accurate image. The correlator a super computer (interferometry) • The resolution of the image increases with the data collection rate. Higher data rates are better; higher resolution is better.

Slide #: 2 2006 November 02 Tuesday SURFnet/JIVE- Gigaport Astronomy Seminar

Introduction to VLBI

Once upon a time...

• Telescopes collected data on tapes. Tapes were heavy and bulky. Someone had to stand next to the recorders and change tapes. The boxes had to be boxed and labeled. They were then sent via postal mail to the correlator facility. Once all the tapes arrived from all the locations, you could begin data analysis. Sometimes tapes were lost/damaged. Sometimes data was not recorded properly onto the tapes. It was not unusual for the time between experiment to the beginning of correlation to be multiple weeks. • Hard drive arrays improved the situation... but only temporarily.

• Today, you can transport the data over the network:

e-VLBI

- electronic VLBI SURFnet/JIVE- Gigaport Astronomy Seminar 2006 November 02 Tuesday Slide #: 3

Introduction to VLBI

Once upon a time...

• Telescopes collected data on tapes… heavy and bulky… postal mail… once all the tapes arrived… tapes were lost/damaged… hard drive arrays slightly improved the situation... • It was not unusual for the time between experiment to the beginning of correlation to be multiple

weeks

. • Today, you can transport the data over the network:

e-VLBI

- electronic VLBI 2006 November 02 Tuesday SURFnet/JIVE- Gigaport Astronomy Seminar Slide #: 4

Introduction to VLBI

Why transport data over the network?

• Using the network to transport data improves science • Eliminate the need to move physical objects • Real time analysis • Ability to identify minor problems in data collection • Hybrid observations • Responsiveness to transient events • Automated observation (hands-off observing) • Once the data is on the network, there is flexibility to investigate different options (move the correlator, multiple correlators, etc.) Slide #: 5 2006 November 02 Tuesday SURFnet/JIVE- Gigaport Astronomy Seminar

Introduction to VLBI

Why transport data over the network?

• Using the network to transport data improves science • Eliminating the need to move physical objects enables: • Real time analysis • Ability to identify minor problems in data collection • Hybrid observations • Responsiveness to transient events • Automated observation (hands-off observing) • Networked data supports flexible analysis 2006 November 02 Tuesday SURFnet/JIVE- Gigaport Astronomy Seminar Slide #: 6

Participating Telescopes and Network Paths

* Image created by Paul Boven, JIVE. Satellite image: Blue Marble Next Generation courtesy of NASA Visible Earth (visibleearth.nasa.gov). *Logical network paths.

2006 November 02 Tuesday SURFnet/JIVE- Gigaport Astronomy Seminar Slide #: 7

Introduction to Correlation

Once upon a time…

• Cost to build correlator… limited flexibility (majority of computation in custom hardware)… preset data input rates… scheduling of scarce resource (correlator)… upgrade cost forces longer life-cycle than desired 2006 November 02 Tuesday SURFnet/JIVE- Gigaport Astronomy Seminar Slide #: 8

Introduction to Correlation

Why “Grid-ify” correlation?

• Grid computing offers promising possibilities: • keep up with input (e.g., LOFAR on BlueGene) • Higher precision and new applications • Better sensitivity, interference mitigation, spacecraft navigation • Can CPU cycles be found on the Grid?

• From 16 antenna @ 1Gb/s (eVLBI) To 1000s at 100 Gb/s (SKA) 2006 November 02 Tuesday SURFnet/JIVE- Gigaport Astronomy Seminar Slide #: 9

Introduction to EXPReS

What is EXPReS?

• EXPReS = Express Production Real-time e-VLBI Service The overall objective of EXPReS is to create a

production

level,

real-time

, “electronic” VLBI (e-VLBI) service , in which the radio telescopes are reliably

connected

to the central

super

computer at JIVE in the Netherlands, via a high-speed optical-fibre communication

network

...

- or Make e-VLBI routine, reliable and realistic for astronomers 2006 November 02 Tuesday SURFnet/JIVE- Gigaport Astronomy Seminar Slide #: 10

Introduction to EXPReS

EXPReS Details

• EXPReS is made possible by the European Commission (DG INFSO), Sixth Framework Programme, Contract #026642 • Project Details • Three year, started March 2006 • International collaboration • Funded at 3.9 million EUR by the • Means: high-speed communication networks operating in real-time and connecting some of the largest and most sensitive radio telescopes on the planet 2006 November 02 Tuesday SURFnet/JIVE- Gigaport Astronomy Seminar Slide #: 11

Introduction to EXPReS

EXPReS Partners

• Joint Institute for VLBI in Europe (coordinator), the Netherlands • AARNET Pty Ltd., Australia • ASTRON, the Netherlands • Centro Nacional de Informacion Geografica, Spain • Chalmers Tekniska Hoegskola Aktiebolag, Sweden • Commonwealth Scientific and Industrial Research Organization (CSIRO), Australia • Cornell University, USA • Delivery of Advanced Network Technology to Europe Ltd. (DANTE), UK • Instituto Nazionale di Astrofisica, Italy • Instytut Chemii Bioorganicznej PAN, Poland • Max Planck Gesellschaft zur Foerderung der Wissenschaften e.V., Germany • National Research Foundation, South Africa • Shanghai Astronomical Observatory, Chinese Academy of Sciences, China • SURFNet b.v., The Netherlands • Teknillinen Korkeakoulu, Finland • The University of Manchester, UK • Universidad de Concepcion, Chile • Uniwersytet Mikolaja Kopernika, Poland • Ventspils Augstskola, Latvia 2006 November 02 Tuesday SURFnet/JIVE- Gigaport Astronomy Seminar Slide #: 12

Introduction to EXPReS

EXPReS Partners

19 partners, 21 telescopes, 6 continents, 7500 km longest baseline 2006 November 02 Tuesday SURFnet/JIVE- Gigaport Astronomy Seminar Slide #: 13

Introduction to EXPReS

EXPReS Partners

Extra Interesting Bits

Do we really need networks?

• Fully loaded carrying capacity of a 747 cargo carrying Blu-Ray DVDs • 37 Tbps • However • Latency: buy 1,488,800 DVDs (€€), burn each (2 years @ 1 second burn/DVD), hand label (lots of Sharpie pens), box DVDs, transport to airport, load, fly (€€€) time, unload (€), sort boxes, read each DVD...

• Packet Loss: rare, but fairly devastating when you lose “one packet” • Every transport is unique, no re-use of media.

Source: http://dltj.org/2006/07/internet2-hopi-network http://walt.lishost.org/?p=344 2006 November 02 Tuesday SURFnet/JIVE- Gigaport Astronomy Seminar Slide #: 15

Conclusion

How much data does e-VLBI create?

• 19 Telescope sites • 1 Gbps data rates • Correlator is currently located in Dwingeloo • fiber cross-section is into the correlator is non-trivial • e-VLBI science runs can last for arbitrarily long periods of time, but 3 weeks runs are not unusual • 19 sites x 1 day x 512 Mbps = 19 sites x 86400 seconds x 512 Mbps = 840,499,200 Mbits = ~105 TeraBytes per day 2006 November 02 Tuesday SURFnet/JIVE- Gigaport Astronomy Seminar Slide #: 16

Introduction to EXPReS - SURFnet and JIVE GigaPort seminar for astronomers T.

Transcript Introduction to EXPReS - SURFnet and JIVE GigaPort seminar for astronomers T.