add a CDEF with LIMIT. CDEF:new=old,100,LIMIT for example Mvg, Erik Maxim Kuleshov schreef: > Hi! > > I could manually dump .rrd, edit xml and then restore it, but may be > there is a tool (third-party?) performing filtering raw values > (already stored in file) for specified boundary, substituting "bad" > values for "unknown"? > >