  The new generation of high-resolution broad-band radio telescopes, like the
Low Frequency Array (LOFAR), produces, depending on the level of compression,
between 1 to 10 TB of data per hour after correlation. Such a large amount of
scientific data demand powerful computing resources and efficient data handling
strategies to be mastered. The LOFAR Two-metre Sky Survey (LoTSS) is a Key
Science Project (KSP) of the LOFAR telescope. It aims to map the entire
northern hemisphere at unprecedented sensitivity and resolution. The survey
consist of 3 168 pointings, requiring about 30 PBytes of storage space. As a
member of the German Long Wavelength Consortioum (GLOW) the Forschungszentrum
J\"ulich (FSZ) stores in the Long Term Archive (LTA) about 50% of all LoTSS
observations conducted to date. In collaboration with SURFsara in Amsterdam we
developed service tools that enable the KSP to process LOFAR data stored in the
J\"ulich LTA at the supercomputer JUWELS in an automated and robust fashion.
Through our system more than 500 out of 800 existing LoTSS observations have
already been processed with the prefactor pipeline. This pipeline calibrates
the direction-independent instrumental and ionospheric effects and furthermore
reduces the data size significantly. For continuum imaging, this processing
pipeline is the standard pipeline that is executed before more advanced
processing and image reconstruction methods are applied.
