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[Quenten Grasso <question208167@xxxxxxxxxxxxxxxxxxxxx>]

Question #208167 on Graphite changed:
https://answers.launchpad.net/graphite/+question/208167

    Status: Open => Answered

Quenten Grasso proposed the following answer:
Hi

I have this exact issue myself, I think I've solved it by using the
following,

The Magical 0.125 I'm not sure were this comes from I've seen this
around a few places and had simular results as yourself,

the scale has to be calculated on the sample time your doing

Sample (divide by) timeinseconds x 8 (bits) = yourscale

For example,

I'm doing 3 second samples so I worked out my scale like this

1 / 3 = 0.3333333333333333 * 8 = 2.666666666666667

Here is snapshot of one part of my url

alias(scale(nonNegativeDerivative(s3_sw1.snmp.if_octets-
GigabitEthernet_0_1.rx),2.666666666666667),'RX')

Also keep in mind you need to setup your whisper storage-schemas.conf as
well to expect your data every x seconds this is why I used the prefix
"s3_" eg,

[real_time_3s_120days]
pattern = s3.*
retentions = 3s:120d

Hope this helps :)

Regards,
Quenten

-----Original Message-----
From: graphite-dev-bounces+qgrasso=onq.com.au@xxxxxxxxxxxxxxxxxxx [mailto:graphite-dev-bounces+qgrasso=onq.com.au@xxxxxxxxxxxxxxxxxxx] On Behalf Of David Michael Pennington
Sent: Monday, 10 September 2012 9:01 PM
To: graphite-dev@xxxxxxxxxxxxxxxxxxx
Subject: [Graphite-dev] [Question #208167]: Graphite SNMP Counter transforms

New question #208167 on Graphite:
https://answers.launchpad.net/graphite/+question/208167

I'm using graphite version 0.9.10 to read ifHCInOctets and
ifHCOutOctets, which I'm polling with the  collectd snmp and
graphite_write plugins; I'm using collectd version 5.1.0.

Data arrives into graphite with no problems; however, I want to graph as
bits-per-second.  To test whether my stats are correct, I started a CD
iso download and watched the download rate... it varied between 1.0Mbps
and 2.0Mbps.

Common-sense tells you that you need to multiply Octets counters by 8 to
get bits; however, it seems that I need to divide by 8 to make graphite
display correctly.

When I multiply by a 0.125 scale factor,
"scale(scaleToSeconds(nonNegativeDerivative(<SERIES>), 60),0.125), the
formula correctly converts to bits-per-second and I see numbers between
1Mpbs and 2Mbps...

When I use a scale-factor of 8, it fails spectacularly; I get readings
of 120Mbps, but I know that's impossible because my circuit is capped at
5Mpbs.

I posted the gory-details (including config files and graph snapshots) here:
http://serverfault.com/questions/425828/graphite-snmp-counter-transforms

Could someone me understand the math such that scale(<series>, 8) fails?

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