Journal of the Institute of Convergence Signal Processing (융합신호처리학회논문지)

The Korea Institute of Convergence Signal Processing (한국융합신호처리학회)
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A Study on Comparison of Massive Data Recording Equipments for VLBI Radio Observation Data

VLBI 전파 관측데이터를 위한 대용량 기록장치 비교에 관한 연구

  • Oh, Se-Jin (Radio Astronomy Division, Korea Astronomy and Space Science Institute) ;
  • Yeom, Jae-Hwan (Radio Astronomy Division, Korea Astronomy and Space Science Institute) ;
  • Roh, Duk-Gyoo (Radio Astronomy Division, Korea Astronomy and Space Science Institute) ;
  • Jung, Dong-Kyu (Radio Astronomy Division, Korea Astronomy and Space Science Institute) ;
  • Hwang, Ju-Yeon (Radio Astronomy Division, Korea Astronomy and Space Science Institute) ;
  • Oh, Chungsik (Radio Astronomy Division, Korea Astronomy and Space Science Institute) ;
  • Kim, Hyo-Ryoung (Radio Astronomy Division, Korea Astronomy and Space Science Institute)
  • 오세진 (한국천문연구원 전파천문본부) ;
  • 염재환 (한국천문연구원 전파천문본부) ;
  • 노덕규 (한국천문연구원 전파천문본부) ;
  • 정동규 (한국천문연구원 전파천문본부) ;
  • 황주연 (한국천문연구원 전파천문본부) ;
  • 오충식 (한국천문연구원 전파천문본부) ;
  • 김효령 (한국천문연구원 전파천문본부)
  • Received : 2018.08.23
  • Accepted : 2018.09.30
  • Published : 2018.09.30
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Abstract

KVN(Korean VLBI Network) introduced the Mark6 system of the MIT haystack observatory as a recorder for data recording up to 32 Gbps for VLBI(Very Long Baseline Interferometry) observation. The Mark6 recorder can record data at up to 32Gbps when two systems and 64 HDDs are installed. However, because of the unique recording method that is characteristic of Mark6, we are introducing a large amount of data into a virtual file system, or using a general RAID method, which causes data loss when reading and transferring files at the highest recording speed or file system have. The Flexbuff system, a software recorder developed by JIVE(Joint Institute for VLBI ERIC), can be configured to operate as a data recorder through RAID configuration and network upgrades. In particular, when installed in the Mark6 system, it can record VLBI data at a maximum speed of 32 Gbps with less loss of data compared to the existing Mark6 by utilizing Mark6 resources well. In this paper, we propose that the existing Mark6 system can be operated as Mark6-Flexbuff by installing jive5ab software, and it is verified through experiment that it can be effectively used for VLBI observation operation through data recording test.

KVN(Korean VLBI Network)에서는 VLBI(Very Long Baseline Interferometry) 관측을 위해 최대 32Gbps 데이터 기록을 위한 기록기로 MIT Haystack 천문대의 Mark6 시스템을 도입하였다. Mark6 기록기는 시스템 2대와 HDD가 총 64개 장착된 경우 최대 32Gbps로 데이터를 기록할 수 있다. 하지만 Mark6의 특징인 독자적인 기록방식을 사용하고 있기 때문에 대용량의 데이터를 가상 파일 시스템을 도입하거나 일반적인 RAID 방식을 사용하고 있는데, 최고 기록속도나 파일 시스템에서 파일을 읽어서 전송할 때 데이터 손실이 발생하는 문제가 있다. JIVE에서 개발한 소프트웨어 기록기인 Flexbuff 시스템은 RAID 구성과 네트워크 업그레이드를 통하여 데이터 기록기로서 동작할 수 있도록 구성할 수 있다. 특히 Mark6 시스템에 설치할 경우 Mark6의 리소스를 잘 활용하여 기존의 Mark6와 비교하여 데이터 손실이 적으면서 안정적으로 최대 32Gbps 속도로 VLBI 관측 데이터를 기록할 수 있다. 본 논문에서는 기존 Mark6 시스템에 jive5ab 소프트웨어를 설치하여 Mark6-Flexbuff로 동작할 수 있음을 제안하고, 데이터 기록시험을 통하여 VLBI 관측 운영에 효율적으로 활용할 수 있음을 시험을 통하여 확인하였다.

Keywords

References

  1. Takahashi F., Kondo T., and Koyama Y., Very Long Baseline Interferometer, Ohmsha, 2000, pp. 35-55.
  2. Thompson, A. R., Moran, J. M., and Swenson, G. W.Jr., Interferometry and Synthesis in Radio Astronomy, 2nd Ed., (New York:John Wiley & Sons), 2001, pp. 289.
  3. Duk-Gyoo Roh, Se-Jin Oh, and Jae-Hwan Yeom et al., "2008 Annual Report on Korea-Japan Joint VLBI Correlator and Receiver Development," Korea Astronomy and Space Science Institute, pp. 3-100, 2008.
  4. A. R. Whitney, "Mark 5 Disk-Based Gbps VLBI Data System," in New Technologies in VLBI, edited by Y. C. Minh, ASP Conference Series, Vol. 306, Astronomical Society of the Pacific, San Francisco, CA, 2003.
  5. http://www.haystack.edu/tech/vlbi/mark6/index.html
  6. T. Oyama et al., "The development and performance of a new 4Gbps disk recorder and eVLBI systems using a 10GbE network," 2008 General Meeting of IVS, 2008. 3.
  7. Harro Verkouter, "jive5ab command set version 1.7," Joint Institute for VLBI in Europe, November 22, 2016.
  8. P. de Vicente, L. Barbas, J. Gonzlez, "Using VDIF in astronomy VLBI observations at the 40m RT. Flexbuff and eVLBI operations," February 20, 2016.
  9. MIT Haystack observatory, "Mark6 system user's manual," November 19, 2013.
  10. Elecs Industry Co. Ltd., "RF Direct Sampler OCTAD Series," 2015.
  11. Se-Jin Oh, T. Oyama, and Jae-Hwan Yeom et al.(2016, December), A Study on the Test Results and Wideband Observing of the Korean VLBI Network, Journal of The Institute of Signal Processing and Systems, 17(2), pp. 83-92.
  12. http://www.vlbi.org/vdif
  13. Jae-Hwan Yeom, Se-Jin Oh, Duk-Gyoo Roh et al(2009, December), Development of Software Correlator for KJJVC, Journal of Astronomy and Space Science, 26(4) pp. 567-588. https://doi.org/10.5140/JASS.2009.26.4.567