[rrd-users] Independent Right Axis

Rick Jones rick.jones2 at hp.com
Wed May 9 23:55:21 CEST 2012

On 05/09/2012 02:46 PM, Chris Mason wrote:
> Hi,
> I can see this topic has come up before in the archives, but are there
> any plans to have an independent right axis which isn't coupled to the
> left that rrdtool can auto-scale?
> I am trying to plot "bits per second" on the left axis and "packets
> per second" on the right axis for the same data.
> On a graph I am plotting ifHCInOctets, ifHCInUcastPkts,
> ifHCInBroadcastPkts and ifHCInMulticastPkts as well as the outbound
> values.
> The relationship between "bps" and "pps" isn't always consistent as it
> is determined by packet size (i.e. small packets will have a larger
> pps rate than larger packets for the same bps). I understand that I
> will probably have to have two passes of rrdtool to first fetch the
> values before using them in the scale parameters.
> Assuming my left axis is scaled automatically then my data could range
> from 1 bps to>10 Gbps. If I take some example data then my inbound
> "pps" rate is usually a factor of 10,000 times smaller using the
> following formula:
> (avg bps) / (avg pps) = scale factor
> However, if I try the same calculation for outbound traffic then I get
> a scale factor of 1,500.
> Would anyone who has done something similar be willing to share what
> they have done or give me some pointers on the best way to go about
> this?

It may not apply 100% to what you want to do, but:


does something similar to what you are describing (though for only two 

rick jones

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