How To Remove Spikes From Cacti Graphs

Log into http://cacti.geant.net/cacti/

Locate the graph with the Spike:

Click on the Spanner icon to the right of the graph to determine the name of the Round Robin Database (RRD) file that requires changing.

In this case the rrd file name is /opt/cacti-0.8.7e/rra/mx1_lon_uk_traffic_in_20683.rrd.

Click on the Magnifying Glass icon to the right of the graph and select the time period you wish to zoom into.

Continue 'zooming' until you can determine the date and time range of the Spikes. In the above case one spike occurred on 19/01/2016 and the other on 26/01/2016 

Using the Epoch & Unix Timestamp Conversion Tool found at http://www.epochconverter.com/ convert the date/times into their UTC equivalent as Cacti stored its date and time in UTC format.

In this case the UTC ranges are 1453161601 - 1453247999 and  1453766401 - 1453852799. We can also see that the data values are in the range of 3x10e12 (3.0T) and 3.5x10e12 (3.5T)

Log into prod-cacti01-fra-de.geant.net 

Change to the /tmp directory and export the data to an XML file format.

rrdtool dump /opt/cacti/rra/mx1_lon_uk_traffic_in_20683.rrd > /tmp/mx1_lon_uk_traffic_in_20683.rrd.xml

Edit the  /tmp/mx1_lon_uk_traffic_in_20683.rrd.xml and find the offending data. Change the values to a more meaningful order of magnitude. Save your changes.

Create a backup of the file you wish to change. 

sudo -u cactiuser mv /opt/cacti/rra/mx1_lon_uk_traffic_in_20683.rrd /opt/cacti/rra/mx1_lon_uk_traffic_in_20683.rrd.bak

Recreate the RRD file using the data from the exported XML file. 

sudo -u cactiuser rrdtool restore /tmp/mx1_lon_uk_traffic_in_20683.xml  /opt/cacti/rra/mx1_lon_uk_traffic_in_20683.rrd

We now need to sync this change with the other production instance of Cacti on prod-cacti02-vie-at.geant.net

sudo -u cactiuser scp -i /home/cactiuser/.ssh/id_dsa cactiuser@prod-cacti02-vie-at.geant.net:/opt/cacti/rra/mx1_lon_uk_traffic_in_20683.rrd /opt/cacti/rra/mx1_lon_uk_traffic_in_20683.rrd