munin supersampling data consolidation graph

Question

I use munin super sampling to get network tx/rx per second. This works fine and it produces the following graph:

You can see the maximum value recorded is 75MBytes per second. Of course you want to know at which second the peak was recorded. But as the graph data is consolidated to 5 minutes average you can just guess.

I can click into it with cgi-graphing and look at the traffic of each second. But you can't just zoom in the biggest 5min average peak as it might not be the 1 sec peak:

Is there a way to give different graph_options on munin or rddgraph, like: do not take average on consolidating data to one data point but use the maximum value. This would make much more sense on supersampling.

Answer 1

You are looking for the graph_data_size plugin config directive, it is hinting at the resolution steps to build the RRD with:

The format is still comma-separated, only the elements are translated:

time_res_1 for time_duration_1, time_res_2 for time_duration_2, ... time_res_N for time_duration_N.

time_res_N represents the step of the RRA. time_duration_N represents the time of RRA frames to keep. The actual number of frames is function of time_res_N. The format for both fields is the same : a number followed by a unit like 134d or 67w.

The units are case sensitive and mean:

• s: second
• m: minute (60s)
• h: hour (60m)
• d: day (24h)
• w: week (7d)
• t: month (31d)
• y: year (365d)

Example:

graph_data_size custom 1d, 10s for 1w, 1m for 1t, 5m for 1y

This will keep full resolution (defined as seconds per interval in the update_rate of the plugin config) for 1 day, scale down to 10-second consolidations for 1 week, further reducing the resolution to 1 minute for 1 month and 5 minutes for 1 year.

Caveat:

graph_data_size is only honored when actually building the RRD anew. If you already have the RRD built, mounting graph_data_size into the plugin's config output will not do anything unless you delete the RRD and plugin state data at the server.