MPIfR Correlator Report (April 2009)
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MPIfR/BKG  MKIV  CORRELATOR  
===========================     

GENERAL

   Current correlator capabilities are listed at:
        http://www.mpifr-bonn.mpg.de/EVN/MK4CORstatus
  

MK IV HARDWARE CORRELATOR

   > Present playback status (both for hardware and software correlator): 
     8 Mark 5As (upgrades to 5B available)
     4 Mark 5Bs
     To be used exclusively with the software correlator:
       2 Mark 5B+ (used in the lab)
       2 Mark 5C  (10GE mezzanine cards will be delivered later)
       8 Mark 5C  upgrades 

   > SDK 8.1 and new Mark 5B software are being tested

   > 2 servers with ~20 TB are used for Internet transfers of VLBI data. 


CORRELATION SOFTWARE

    > A new tarball with improvements was installed.



DiFX SOFTWARE CORRELATOR

   > The compute cluster was upgraded to 60 nodes with about 500 compute
     cores.
     - 4 TFlops
     - 4 to 24 kW power dissipation (idle - fully loaded)
     - 40 TB disk space
     - 20 Gbit Infiniband interconnect

   > The standard "NRAO" version of DiFX is installed.

   > The correlation of a multi-field VLBA observation has been the first big
     test case at Bonn. About 3 TB of correlated data have been generated so
     far. Also a few problems with DiFX were fixed. A new post-correlation
     averaging mode for multi-field VLBI observations is being implemented by
     Estrella student John Morgan from Bologna, who is visiting Bonn from
     January to May. It is expected that this software will replace the flaky
     source position shift software in AIPS.

   > Pulsar VLBI data was correlated successfully.

   > Phase-cal is being implemented by a masters student in collaboration with
     Pogrebenko (JIVE) and Wagner (Metsähovi).

   > The 2nd stage of geodetic verification will be continued after the
     implementation of phase-cal.

   > John Morgan has started to investigate how an interface to MK IV analysis
     software can be realized.

   > Astronomical correlation will switch over to the DiFX software correlator
     in the first half of 2009. 

   > Up to 16 Mark 5s will initially be connected to the software correlator
     via 1 GE.

OPERATIONS

   > 80 750 GB PATA disks were bought at the end of 2008 and are were used to
     upgrade smaller modules with 120 GB disks. 50 TB were added to the EVN
     pool.

   > 24 SATA 8-pack kits were procured at the end of 2008. 50 1.5 TB disks
     (per disk 95 € + VAT) will be purchased now, which will add 75 TB for VLBI
     recording.

E-VLBI

   > The geodesists transfer data from several stations regularly to Bonn for
     correlation. This is still labour intensive. Once the software correlator
     can be used, e-VLBI transfers will become a standard way for rapidly
     transferring data to the correlator.

   > On November 19, inauguration of the Effelsberg fibre connection took
     place. Amongst others EU officials attended.

   > The Mark 5A unit has been equipped with an additional dual 1 GE card
     which allows link aggregation. Data transfers of 1024 Mbit with this
     configuration were successfully tested over the 10 GE line.

OTHER

   > A VSI to/from 10 GE converter board for the DBBC is being developed. Two
     prototype boards have been ordered.

   > A technician was hired for one year on a 50% basis to work on the
     production of DBBCs.

   > Parts of the DBBC production are continuing at Bonn.

W.Alef