[mrtg] Re: can i keep more data

[Chris Robb]

I saw a few questions that went unanswered to the list on this, so I
thought I'd share my findings.

When the reference pages refer to "base interval count", this refers
to RRA 0, as created when upsizing from MRTG to RRD. So, I believe the
original question was the user wanting to keep 2 years worth of 5 minute
data. If I'm correct, "RRDRowCount[ezwf]: 210240" will take care of this,
given a 5 minute polling interval. If you want to do this after the MRTG
files have been converted to RRD, you have to use the rrdtool resize
command and add 20640 rows to RRA 0.

When you resize, it adds the rows to "the past". By that, I mean, if you
do a dump of the rrd file right after you insert rows, you'll see two
years worth of 5 minute polling intervals with NAN, with only the last 600
rows containing data. Once you start collecting against that, the new data
will push out the old data.

Somone asked about changing the other RRAs. Use Resize for that as well.
Do a "rrdtool info" on the RRD file you want to change and note the RRA
number you want to insert rows.

Also, the reference mentions that by default upsizing holds about 1 days
worth of high resolution (5 minutes) of data. Since most people run mrtg
on a five minute interval, and since there are 600 rows created in RRA 0
by default, should this be changed to say 2 days with of data?

I just modified the backend to the Abilene Animated Traffic Map to run off
RRD, which was a pain since our backend is all hacked together. One of
these days I might be able to share it, if I ever get it cleaned up
enough. :)

-Chris

Chris Robb
Indiana University Global NOC
Abilene/TransPAC Network Engineer
chrobb at iu.edu  Desk: 812-855-8604 Cell: 812-325-8199

On Tue, 15 Oct 2002, Tobias Oetiker wrote:

>
> Today Brander, Eric wrote:
> from reference.pod
>
> head2 RRDRowCount
>
> This affects the creation of new rrd files. By default rrds are created to
> hold about 1 days worth of high resolution data. (plus 1 week of 30 minute
> data, 2 month of 2 hour data and 2 years of 1 day data).  Whith this Keyword
> you can change the number of base interval entries configured for new rrds
> as they get created. Note that you must take the interval time into account.
>
> Example:
>
> RRDRowCount[ezwf]: 1600
>



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