Time Decay

dischide · Post by **dischide** » Mon Jan 07, 2008 8:44 am

I am running cacti version 0.8.6.j. I noticed that my daily bandwidth graphs are accurate. Then there is the time decay when I get into my weekly graphs. It gets progressively worse from weekly to monthly to yearly.

For instance I will graph a bandwidth spike of 60 mb. Then in a week that same spike is now 30 mb. Then in a month it will decrease down to 10 mb. So the data becomes inaccurate.

Shouldn’t the max always remain valid? This happens on all of my graphs (bandwidth, CPU utilization, load averages, etc …). Has anyone, else, seen this? What can I do to prevent this from happening?

BSOD2600 · Post by **BSOD2600** » Mon Jan 07, 2008 1:40 pm

This is due to rrdtool consolidating the data over time. Read in the documentation site on how you can help prevent this and extend the amount of history rrdtool keeps.

dischide · Post by **dischide** » Wed Feb 06, 2008 12:36 pm

Ok, thank you for showing me this. RRDTool performs consolidation to combine raw data to save space.

I have been looking for away to stop this. I have not been able to find one, yet. Does have one know how to stop this so I can have accurate data?

http://www.cacti.net/downloads/docs/htm ... orage.html

Post by **gandalf** » Wed Feb 06, 2008 12:39 pm

Please find some words on thsi topic here
Reinhard

dischide · Post by **dischide** » Wed Sep 10, 2008 3:18 pm

I read "Howto View Historical Data after Consolidation" and I cannot figure out how to see the MAXimums. It was mentioned there was an attachment to this topic. However, I did not see that either.

What, and how, would I modify so that I can graph the MAXimums in all views (Daily, Weekly, Monthly, and Yearly)?

Thank you

dischide · Post by **dischide** » Thu Sep 11, 2008 11:07 am

What if I just graphed the Maximum (would that work)? It seems like it should.

Post by **gandalf** » Thu Sep 11, 2008 12:08 pm

That would be a solution. Personally, I prefer to keep the graphs shown AVERAGE and ADDING the MAX as an additional graph item.
So I see both on a single graph.
Doing so AND plotting ifOut Traffic to the negative y-axis makes very nice graphs
Reinhard

dischide · Post by **dischide** » Tue May 19, 2009 1:42 pm

I did what you suggested. The graph looks really nice and is accurate thank you for you help.

NWA Cacti Admin · Post by **NWA Cacti Admin** » Wed May 20, 2009 7:09 pm

Dischide:

Could you post a sample of your graph? I'd like to see how you did this.

TIA

Post by **gandalf** » Fri May 22, 2009 2:18 am

Such a template is published at the 4th link of my sig
Reinhard

dischide · Post by **dischide** » Fri Jul 17, 2009 11:39 am

In graph templates > Interface (bits/sec)
I added the max as a line

For inbound traffic
Graph Item Type - line
Consolidation Function - MAX
CDEF Function - Turn bytes into bits
Value - MAX:
GPRINT Type- exact values

Then for outbound traffic you do the same, only you make it negative:
CDEF Function - Turn bytes into bits, make negative

Make sure anything you graph, for outbound, you make negative. And anything you print on the graph (GPRINT) you keep positive. It make is easier to read.

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