When GFTAVMA finds the flag in the SMF record that indicates a data set has been IDRC compacted, it uses the actual IDRC value for its calculations instead of the value you specified with the IDRCFACTOR keyword.

However, SMF records do not have a flag to indicate software compaction. Since GFTAVMA reports on the size of data transferred and cannot tell if a data set is already software compacted or compressed, the data set size could be larger than the data set transfer size. For data sets that have been software compacted, the volume mount analyzer does not know the actual size of the data sets or whether or not they have been compacted.