RRD graph explain

Applications IP Networking
1

Hi all,

I have a graph sent from customer.
And i just know this is created using rrdtool after search the web.
Based on this graph,

  1. I read that it can be set, but is it possible to know what is the time step for each point in this graph? is it 5 minutes or something?
  2. Let says it is 5 minutes, then is it true if I say RRD tool measures the average value every 5 minutes?

Thanks for the help.

2

Hi.

You can find the step using:

rrdtool info yourdbname.rrd | grep step

If the step is 300 (5 minutes) then rrdtool will average data (or whatever consolidation function your db is created with) given over any five minute period.

Unless I'm mistaken, the only way to change the step is to:

rrdtool dump yourdbname.rrd > yourdbname.xml
(edit the XML file)
rrdtool restore yourdbname.xml yourdbname.rrd

This link explains quite well how the step works.

Of course, this is all on the understanding that they provided you with the RRD database file, and not just the PNG graph file.

1 Like
3

Hi Scottn,

Thanks a lot for your info.
The problem is I have nothing but a graph :smiley:
And I don't have the environment.

Ok, so can you tell me generally what will be the consolidation function used?
Is it average value? And is it possible (or is it common) if the consolidation function is set only to capture the data for each time step?

I mean like :
at 00.05 : capture the value at 00.05
at 00.10 : capture the value at 00.10

Do you think that is common?

4

I would say it's (probably) the average value in graph.

There is a LAST consolidation function which gets (as the name suggests) the last value for each step. I don't know if it's common - I've never used it.

It would be nice if they included some info in the graph explaining what the data means.

1 Like
5

Hi Scottn,

Ok, I got it.
Many thanks for your clear explaination.
Say hi to Zurich citizen :smiley: