[rrd-users] Re: Database never updates

Clay Chambers claychambers at yahoo.com
Tue May 25 19:30:24 MEST 2004

Hi Geoffrey,

I'm by no means an expert on RRDTool, but allow me to offer a few suggestions
based on my own experience.

1. Use COUNTER type rather than GAUGE.  A counter is made for this sort of
thing, whereas you must jump through some hoops to get a delta byte count for a
GAUGE.  Just update your rrd with the current byte count and let the COUNTER
handle the rest.

2. Perhaps your ifconfig wrapper isn't working quite like it should.  If you're
using a Linux box, try 'cat /proc/net/dev' instead.  It's much easier to parse
as there is one line of output per interface.  

3. It's unnecessary to divide by 1024 (or anything else for that matter).  The
grapher will automatically append the proper suffix (k or M) to your vertical
labels for you.  This will dictate that you change your vertical label from
"KBytes/second" to "bytes/second", but I think you'll be happier in the long
run.  Of course, just multiply by 8 within your CDEFs if you'd prefer a
bits/second measurement.  Also, when dealing with network traffic, use the
default base of 1000, not 1024.  1000 bytes = 1 kbyte.

4. It's unnecessary to divide by 60.  RRDTool uses your update time delta to do
the averaging for you.  Just update your rrd with the current timestamp and
current byte counts, and you'll be fine.  No other manipulations are necessary.

5. Use GPRINTs instead of a COMMENTs in your graph.  That way you won't have to
bother with  extra calculations.  i.e. "GPRINT:outbd:AVERAGE:Out %02.2lf%S".

I hope this helps.


> -----Original Message-----
> From: rrd-users-bounce at list.ee.ethz.ch
> [mailto:rrd-users-bounce at list.ee.ethz.ch] On Behalf Of Geoffrey Gallaway
> Sent: Monday, May 24, 2004 11:19 AM
> To: rrd-users at list.ee.ethz.ch
> Subject: [rrd-users] Database never updates
> Hello, I'm trying to create a bandwidth utilization graph for my router.
> I don't want to install SNMPd and use up the little RAM I have in the
> box so I just decided to write a shell script to wrap ifconfig. However,
> it's not working, the database is created but no values are ever
> entered. just ton's of NaN's. The script is below:
> #!/bin/sh
> if [ ! -a /home/geoffeg/rrdscripts/eth0.rrd ]; then
>         rrdtool create /home/geoffeg/rrdscripts/eth0.rrd \
>         --step 60 \
>         DS:inbound:GAUGE:120:0:U \
>         DS:outbound:GAUGE:120:0:U \
>         RRA:AVERAGE:0.5:1:43200
> fi

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