CODEWITHSUNDEEP
rrdtool
Martin
Martin

Reputation: 1177

Is the rrdtool RRA XFF value useless if RRA step is 1?

According to rrdcreate manual, the RRA definition has the following syntax:

RRA:{AVERAGE | MIN | MAX | LAST}:xff:steps:rows

XFF(xfiles factor) defines what part of a consolidation interval may be made up from UNKNOWN data while the consolidated value is still regarded as known. Am I correct, that if the step is 1, then XFF value doesn't matter because single PDP is used to build the RRA entry, i.e this single PDP is either present or not? For example, both RRA:AVERAGE:0:1:12 and RRA:AVERAGE:0.9999:1:12 are equal?

Upvotes: 1

Views: 602

Answers (1)

Steve Shipway
Steve Shipway

Reputation: 4027

Short answer is, yes, sort of. When you have 1cdp=1pdp then the amount of data present in a CDP can logically only be 100% or 0%, and so all xff values in the range 100>xff>=0 are identical. Note that we exclude 100 from this range! An xff of 100 would not make sense unless your computer has a usb-attached crystal ball...

However this parameter becomes much more important once lower-resolution RRAs start to consolidate data over large windows, which is the primary function of the RRA.

Upvotes: 2

Related Questions