Re: [munin-users] Data retention

[Renaud M. <ren...@gm...>]

Hello
Le 27/06/2013 à 23:14, Berend a écrit:
> this is a question about the data life in Munin.
> 
> I am monitoring various sensors and data feeds, and would like to keep an
> historic archive. I thought that after one year the data might be recycled
> as the RDD is fixed length and that is the largest time span displayed by
> the graphs. Searching around, I found it might even be two years, but
> nevertheless in a few months I will need to have a solution.

The default id 1 year, but since munin 2.0 the size of the RRD files
created by munin can be configured with the graph_data_size parameter in
munin.conf

see http://munin-monitoring.org/wiki/format-graph_data_size

But that parameter will only be used when creating new RRD files, your
existing files won't be changed.

The rrdtool command has some functions which can be used to create bigger
RRD files with your existing data.

With the dump/restore (rrddump/rrdrestore) functions, you can export one
RRD file to XML and create a new RRD file from that XML. You can modify
that XML with appropriate tools (like XSLT) to add more values in the
<database> element (you must have the same number of values for rra with
the same pdp_per_row).

There is also a resize (rrdresize) function which can be used to grow or
shrink one RRA in an RRD file. But it also create a new RRD file and can
only resize one RRA, so to resize all the RRAs you have to play with
temporary files then rename the final file to the original name.

I have a script that uses rrdtool resize multiple times to grow all the RRA
in a RRD to the desired size, I can post it if you are interested.

Of course, overwriting/renaming RRD files should not be done while
munin-update is running.

> The question though is, does Munin keep an option to backup the data as
> soon as the RRD file is full? I can't seem to find any discussion
> regarding this topic.

I don't think so, but it will happily use bigger RRD files like described
over, I have been doing it without problems for 2 years.

> Also, am I right in believing munin is not suited for viewing
> archived/historical data?

No, with munin 2.0 and CGI graphing, you can use the zooming functionality
to generate graphs with older data, if the RRD files contains them.


-- 
Renaud MICHEL
defimedia S.A.