The Selected Data Set Activity (Bytes) report shows the total number of bytes per FTP client or server for the data set chosen. Only data transfer sessions are included. This report shows you which FTP data sets are the most heavily used at your installation in terms of number of bytes transferred.
The total number of sessions may or may not correlate with the period of highest amount of bytes transmitted. For example, there may be many FTP sessions that perform non-data transfer activity (RENAME), or many failed FTP sessions. You may wish to view the Selected Data Set Activity (All Sessions) to obtain a balanced picture of activity.