[rrd-users] Re: Manipulating and Graphing Data

Simon Hobson linux at thehobsons.co.uk
Tue Oct 31 19:35:28 MET 2006

Tony Varriale wrote:

>  > Closer, but it uses the values supplied AND THE TIME INTERVALS to
>>  work out the rate over each interval defined in your rrd. If your
>>  updates EXACTLY match the time intervals then the rate stored will
>>  match the value you put in, otherwise it will be adjusted.
>Right, which is why when I use GAUGE for this specific application, the
>value is preserved.  But, I would like to take the current and previous
>gauge value and subtract them to get a new value.  Then, graph that new
>value.  Once I figure out how to do that, I'm sure there will be some odd
>issues such as counter flips.
>The math that is performed on these values with other data types is not
>useful to me.  It appears GAUGE would be the only one that would work.

So let me get this right, if you feed in 0, 400, 800 at t=0, t=i, 
t=2i, you expect to get out <something>,400,400. I believe that can 
be achieved with the count or derive types. In a couple of 
applications at work, I feed in byte counts from iptables accounting 
rules and use derive - the output I get is the rate (bytes/second) 
which I can scale by multiplication (eg if I multiply by 300 then I 
get bytes/rra interval).

As I understand it, using derive, if the counters are reset (ie 
change from a number to a smaller number, such as when I reboot or 
reload iptables rules) then it will assume that you've 'lost' that 
interval rather than assuming you've wrapped around (very large 
positive value) or reduced (large negative value).

Unsubscribe mailto:rrd-users-request at list.ee.ethz.ch?subject=unsubscribe
Help        mailto:rrd-users-request at list.ee.ethz.ch?subject=help
Archive     http://lists.ee.ethz.ch/rrd-users
WebAdmin    http://lists.ee.ethz.ch/lsg2.cgi

More information about the rrd-users mailing list