The KVN VLBI data have been correlated using a POLARIS cluster using the DiFX (Distributed FX) software. POLARIS is the name of the third generation of the HPC cluster in the KASI. It is in a correlation room at the Jangyoung-Sil Hall. It is composed of one frontend node (IBM System x3750 M4), 35 compute nodes (IBM System x3530 M4). The frontend has four Intel Xeon E5-4650 processors (8 cores per processor) and 96GB memory. Each compute node has two Intel Xeon E5-2470 processors (8 cores per processor) and 48 GB memory. The total number of cores and memory are 592 and 1776 GB. The frontend and compute nodes are connected with a FDR (56Gbit/sec) Infiniband switch. The total usable disk space is around 600TB.
The DiFX software correlator provides quite flexible correlation modes. You can request the accumulation time and the frequency resolution appropriate for your science purpose. The default accumulation time, however, is 0.8 seconds and the default frequency resolutions are 16MHz/256 for continuum observations and 16MHz/512 for line observations.
Due to the delivering time of disk packs from the sites to the correlation center, data copy, and correlation itself, it takes about one month for a PI to get his/her FITS files. Once correlation is finished, an email notification will be given to the PI. It includes on how to get the FITS files.