
The default RRA stores primary data points for a month. More RRA can be added for a quarter and a year. The created RRD is for an acquisition period much less than a month, typically about some hours or a few days.
This constructor neads an argument named step which is the period of acquisition.
The natural step units are hour(h) and day(d),
although second(s),
minute(m) and week(w) are allowed.
$creator = RRDTool::Creator::MonthPDP(-step => "1d") ;
$creator->add_RRA(-duration => "quarter") ;
$creator->add_RRA(-duration => "year") ;