[rrd-users] rrdtool fetch question- what is what?

John Giordano isaac at netos.com
Sat May 17 01:11:38 MEST 2003

greetings list,
we recently got some weird results from querying a .rrd in regards to the amount of bandwidth a customer of ours supposedly pushed.
we are attempting to verify the results.
the perl script i wrote that goes thru and queries the rrd's and then shoves the results to mysql came up with this:
foo moved:  39.7927987740375 GigaBytes for 4/1/03 2:30pm to 5/1/03 2:30pm (this would be for both INBOUND and OUTBOUND)
i went back to the .rrd on the disk and did this:
serengeti# cat working-cmd-month-stdout-IN
./rrdtool graph /dev/null  --start '4/1/03 2:30pm' --end '5/1/03 2:30pm' DEF:inoctets=myrouter.rrd:ds0:AVERAGE CDEF:in=inoctets,8,* PRINT:in:AVERAGE:"%lf"
##This is inoctets multiplied by 8 thereby giving me bits
serengeti# ./working-cmd-month-stdout-OUT
65164.533407 / 8 * 86400 * 30 = 21113136000
serengeti# ./working-cmd-month-stdout-IN
65978.750124 / 8 * 86400 * 30 = 21376872000
42490008000 bytes = 39.5719036459923 GigaBytes.  RRD Matches script pretty much
i am still paranoid tho...the customer has never, ever moved this much data in a month.  so now i'm freaking out trying to figure out how to look inside the .rrd and see what's going on.
as further tests, I compared the results to the frontend we run for RRDTool, Steve Shipway's routers.cgi, and they seem to jive.
basically, he has a function that allows you to look at the last calendar month and this is what it reported:
ShipWay's Script says for last calendar month on 5/12/03 3:50pm:  (This would be for 5/12/03 back one calendar month)
66.665 GigaBytes.....so our results of :  39.7927987740375 GigaBytes from 4/1/03 to 5/1/03 seems within the realm of possibilty.
but again, the customer never moves this kind of data and now looking at his graphs, the interface on the router, etc - he is back to normal bandwidth- really small stuff compared to before.
Then... (sorry for the long email)
I ran this 95th percentile script that a guy on this list wrote (which rocks by the way- thank you):
going to run 95th percentile script on it from 4/1/03 to 5/1/03
serengeti# ./95_munge.pl -q -d -f myrouter.rrd 
/usr/bin/rrdtool fetch -s 1050254634 myrouter.rrd AVERAGE
Results are in BYTES
ds0:105.10689475 - IN is ds0.
ds1:409.69688889 - OUT is ds1.  And from our perspective this would be packets heading towards Murph from the Net.
which is small....
409.69688889 bytes (would you guys say this makes any sense? 409 bytes for 95th percentile and the .RRD says he moved 39 Gigs in that month?)
bits 3277.57511112 
bytes 409.69688889 
kilobits 3.20075694445313 
kilobytes 0.400094618056641 
megabits 0.00312573920356751 
megabytes 0.000390717400445938 
gigabits 3.05247969098389e-06 
gigabytes 3.81559961372986e-07 
last question is on the rrdtool fetch command I ran.
basically, I have two questions:
1) what can I do with this data in order to see if the aggregate traffic I am calculating is correct?
2) what are the results in?  bits?  and then what is the timeframe between each sample?
here are the outputs of the rrdtool fetch and rrdtool info on this .RRD (actually the majordomo has an email size limit so I am trying just this first)
many thanks to whatever insight you can give,

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