ECHOMOP makes substantial use of disk space throughout the reduction process. This is due to the intermediate storage of information in the reduction file. Much of the information stored is on a per-order basis. For data frames with many orders the disk usage may be substantially reduced by the following:
% cp $ECHOMOP_SOURCE/ECH_COMPACT.DEF ECH_RDCTN.DEF
% source $ECHOMOP_EXEC/echomop.csh (UNIX) ICL> LOAD ECHOMOP_EXEC:ECHOMOP (ICL)
This must be done before any reductions are embarked upon as it will not save any space retroactively on reductions already in progress.
When this procedure is used, it is essential to ensure that the per-order mode of operation is used and that the orders are fully processed one-by-one. i.e., flat-field, model sky, extract, and save result for order 1, then for order 2 etc. This is because the compact version only stores reduction arrays for the last processed order. Thus flat-field modelling order 3 and then order 4 would cause the calculated model for order 3 to be overwritten by the one for order 4.