Hi team!
we see that when we are facing a performance graph, punctually on a peak that catches our attention, if we zoom in by narrowing the time range, that same peak changes and shows other values, besides perching on another moment. We found it very confusing and not apporting good data that let us make our annalisys. It is normal for graphics to behave in this way?
Ill let you attached 3 examples of what i've being talking about.
Thanks in advance!
Performance graphs doesn't show real data
Performance graphs doesn't show real data
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Re: Performance graphs doesn't show real data
This just looks like your plotting a delta value (changes only) so a negative value would be proper but not what you want. I can see if your plugin supports doing it that way but I will need these things:
Please attach these files so that I can review them:
- Change HOSTNAME and SERVICENAME accordingly
Please attach these files so that I can review them:
- Change HOSTNAME and SERVICENAME accordingly
Code: Select all
/usr/local/nagios/share/perfdata/HOSTNAME/SERVICENAME.rrd
/usr/local/nagios/share/perfdata/HOSTNAME/SERVICENAME.xmlRe: Performance graphs doesn't show real data
Sorry for the delay, there you got the files.
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Re: Performance graphs doesn't show real data
The data that is displayed in the performance graphs come from data files called Round Robin Databases (RRD).
Those files are a fixed size and to store the data for long periods, it has to be averaged out with the previous data.
When that happens, there will be a loss of accuracy and when you specify a time range further back in time, there will be less accuracy and the data will be different.
The settings in the RRA file controls how the data is stored in the rrd files which it used to display the graphs.
The entry
RRA:AVERAGE:0.5:1:2880
Will store 2880 entries of the average data in the rrd file with 1 minute step for each entry which equals 48 hours of data.
These entries will be the most accurate.
After the 48 hours, the last entry will be removed and added to the next section. It will be averaged and some accuracy will be lost.
If you display a graph in this timeframe, this is the data you are looking at.
RRA:AVERAGE:0.5:5:2880
The above entry Will store 2880 entries of the average data in the rrd file with 5 minute step for each entry which equals 10 days of data.
Since the data is an average of 5 of the one minute entries, the results will be slightly less accurate.
If you display a graph for example last 7 days, this is the data you are looking at plus the above entries.
RRA:AVERAGE:0.5:30:4320
The above entry Will store 4320 entries of the average data in the rrd file with 30 minute steps for each entry which equals 90 days of data.
Since the data is an average of 6 of the 5 minute entries, the results will be slightly less accurate.
If you display a graph for example last month, this is the data you are looking at.
RRA:AVERAGE:0.5:360:5840
The above entry Will store 5840 entries of the average data in the rrd file with 360 minute steps for each entry which equals 4 years of data.
Since the data is an average of of the 30 minute entries, the results will be slightly less accurate.
If you display a graph for example last year, this is the data you are looking at.
The other entries are the same settings but for the MAX data for a check and the MIN data for a check.
Depending on the time frame you are viewing and how many points can be displayed on your screen because of the resolution, the application that displays the data, has to sample the rrd file's data and plot it and that is why there are variances in the graphs.
Those files are a fixed size and to store the data for long periods, it has to be averaged out with the previous data.
When that happens, there will be a loss of accuracy and when you specify a time range further back in time, there will be less accuracy and the data will be different.
The settings in the RRA file controls how the data is stored in the rrd files which it used to display the graphs.
The entry
RRA:AVERAGE:0.5:1:2880
Will store 2880 entries of the average data in the rrd file with 1 minute step for each entry which equals 48 hours of data.
These entries will be the most accurate.
After the 48 hours, the last entry will be removed and added to the next section. It will be averaged and some accuracy will be lost.
If you display a graph in this timeframe, this is the data you are looking at.
RRA:AVERAGE:0.5:5:2880
The above entry Will store 2880 entries of the average data in the rrd file with 5 minute step for each entry which equals 10 days of data.
Since the data is an average of 5 of the one minute entries, the results will be slightly less accurate.
If you display a graph for example last 7 days, this is the data you are looking at plus the above entries.
RRA:AVERAGE:0.5:30:4320
The above entry Will store 4320 entries of the average data in the rrd file with 30 minute steps for each entry which equals 90 days of data.
Since the data is an average of 6 of the 5 minute entries, the results will be slightly less accurate.
If you display a graph for example last month, this is the data you are looking at.
RRA:AVERAGE:0.5:360:5840
The above entry Will store 5840 entries of the average data in the rrd file with 360 minute steps for each entry which equals 4 years of data.
Since the data is an average of of the 30 minute entries, the results will be slightly less accurate.
If you display a graph for example last year, this is the data you are looking at.
The other entries are the same settings but for the MAX data for a check and the MIN data for a check.
Depending on the time frame you are viewing and how many points can be displayed on your screen because of the resolution, the application that displays the data, has to sample the rrd file's data and plot it and that is why there are variances in the graphs.
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