(PECL rrd >= 0.9.0)
RRDCreator::addArchive — Adds RRA - archive of data values for each data source
Adds RRA definition by description of archive. Archive consists of a number of data values or statistics for each of the defined data-sources (DS). Data sources are defined by method RRDCreator::addDataSource(). You need call this method for each requested archive.
Definition of archive - RRA. This has same format as RRA definition in rrd create command. See man page of rrd create for more details.