Transcript SA1: technical progress Arpad Szomoru JIVE e-VLBI: operational improvements • Overall improvement in first 16 months: • • • • • • • • • Robustness Reliability Speed Ease of operation Station feedback Minimizing data loss by careful.

SA1: technical progress
Arpad Szomoru
JIVE
e-VLBI: operational improvements
• Overall improvement in first 16 months:
•
•
•
•
•
•
•
•
•
Robustness
Reliability
Speed
Ease of operation
Station feedback
Minimizing data loss by careful scheduling
Increase of production data rate from 128 Mbps to 256 Mbps
6-station fringes at 512 mbps
Inclusion of Metsähovi and Medicina telescopes
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #2
e-VLBI: data rate improvements
Number of telescopes @ data rate
640
Data rate (Mbps)
512
1
2
3
6
5
384
256
6
4
Aggregate data rate
128
3500
0
-128
Jan-04
Aug-04 Feb-05 Sep-05 Mar-06
Oct-06
Apr-07
Nov-07 Jun-08
Data rate (Mbps)
Jun-03
3000
2500
2000
1500
1000
500
0
Apr-04 Sep-04 May-05 Sep-05 Oct-05 Nov-05 May-06 Aug-06 Dec-06 Feb-07 Jun-07
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #3
Operational e-VLBI: latest results
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #4
The EVN MarkIV correlator
Custom-made hardware,
~500000 lines of C++ code
Designed and built on tape
technology, only recently
adapted for disk-based
recording
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #5
Work packages
• Standard e-VLBI correlator mode:
• Wall-clock time vs ROT
• Centralized control
• Rapid response/ToO functionality:
• Real-time monitoring/feedback/analysis
• On-the-fly adjustment of observational/correlator
parameters
• Improved amplitude calibration
• Data transport issues
• Lightpaths: guaranteed (high) bandwidth
• Transport protocols (modified TCP, UDP-based,
VSI-e…)
• Hardware issues
• New control computers (reliability, speed)
• Replacement of SUs (cause of much misery)
• Networking hardware (router, interfaces)
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #6
e-VLBI correlator mode: control interfaces
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #7
Monitoring tools: Integrating fringe display
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #8
Monitoring tools: Data status monitor
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #9
Monitoring tools: Data status monitor
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #10
Rapid adjustment of correlator params: vex editor
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #11
(near) Real-time analysis: streamlining of post processing
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #12
Web-based Post-processing
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #13
Hardware
New control computers
• Solaris AMD servers, redundant power supplies
• Interchangeable for maximum reliability
• Cut down dramatically on (re-)start time
• Removal of single points of failure
Mark5 upgrade
• Original Mark5s woefully under-powered (Pentium
PIII…) New dual processor motherboards, memory,
power supplies
• Mark5A→B: new streamstor cards, new serial links
(optical and coax), Correlator Interface Boards
• Elimination of Station Units, VSI compliance
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #14
Upgrade of network at JIVE
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #15
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #16
SA1: the next 18 months
All personnel in place, at JIVE and JBO
Main focus:
•
•
•
•
Adaptive scheduling
Increasing the operational data rate
Improving flexibility and robustness of correlation
New telescopes
• Inclusion of eMERLIN telescopes
• Re-assessment/refinement of deliverables
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #17
Specific tasks
Crucial:
• fast/adaptive (re-)scheduling
• Transform EVN into a truly flexible instrument
• Reaction time of hours
• Remote control of widely different telescope control
systems
• Safeguard local operational constraints
• hard/software upgrade
• Phase out aging Station Units, cause of much misery
• Involves large software effort
• VSI compliance
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #18
Fine-tuning of deliverables
• Use of WSRT synthesis data for e-VLBI calibration
(absolute flux calibration, polarization calibration,
source selection)
• Space craft tracking correlator mode
• On-the-fly fringe fitting
• Real-time download and extraction of station
information
• Automated correlator diagnostics
• Removing/adding stations from the correlation
process on the fly
• Investigating a 1024M sub-array
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #19
Connectivity improvements:
• Use of new/modified transport protocols, lightpaths across
Europe
• Increase granularity of data streams to optimize utilization
of available bandwidth
• Increase of sensitivity and resolution through addition of
telescopes: Effelsberg, Yebes, Shanghai
• Improving global connectivity: South-America, Puerto
Rico, China, Australia
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #20
Global connectivity:
• Arecibo: 64 Mbps real-time operations in the past,
currently < 32 Mbps. New submarine cable facilities in
near future…
• Australia: 4 LBA telescopes connected at 1 Gbps.
Lightpath to Europe via Canada will be available next
Monday. Issues with format conversion (VSI-Mark5BMark5A+), command interfaces, long haul transport
• First tests (not via lightpath): interface seems to work,
format conversion unclear as yet, but yellow leds at 64
Mbps (from three telescopes)
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #21
e-VLBI to China
ORIENT: 2.5 G
TEIN2: 622 M
155 M
100 M
1G
34 M 2.5 G
50 M
1G
2.5 G
1G
622 M
HKOEP SURFnet
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #22
e-VLBI to China (2)
• Lightpath Sheshan (near Shanghai) – JIVE in place (via
HongKong, Chicago). RTT 360 ms.
• Test results (iperf)
• 930 Mbps Seshan – Hong Kong (!!)
• 400 Mbps Hong Kong – JIVE
• ~100 Mbps Seshan – JIVE
• But… issues with security machines, shared bandwidth,
reservation of timeslots needed
• New lightpath via Siberia available since last Monday
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #23
e-VLBI to China (3)
• First operational results: impossible to reach 32 Mbps
• Old Linux kernel, TCP Reno, lossy connection, very long
RTT
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #24
Next big issue
• Long haul transport *not* via lightpath: need either
modified TCP or UDP based protocol
• New streamstor libraries will be available real soon now:
disable congestion control
• Mark5A code has been fiddled to work with plain UDP
again
• Collaboration with Manchester to fold VLBI_UDP into
Mark5A code is ongoing
• Will have to work before APAN meeting demo…
2007 June 28
Arpad Szomoru, eVSAG, Gothenburg
Slide #25