It is used to save the archives on FD. The saving is realized in incremental mode (only new or modified files are written), compressed (six months activity of an average laundry occupies only one FD) and swift (30 sec. or less to record it.
The back-ups are never used except in case of failure of PC with subsequent date loss. In that case, the lack of an archive copy causes the loss of working days since it's impossible to conclude the operations in course.
The daily habit of saving a back-up protects from such a risk and limits the eventual damage only to the substitution of faulty components.