[rrd-users] Re: Partial data = no graph

Serge Maandag serge.maandag at staff.zeelandnet.nl
Sat May 24 10:32:02 MEST 2003

Every time source one has a value, source two is nan.
Every time source two has a value, source one is nan.

nan + value = nan.

Therefore you have to set the nan values to 0.


To see real nan's you could extend this to have it say: 
if both are nan, the total is nan, else it is the value of the one that is not nan.

For a 95th percentile value you would have to alter the script posted here a while back
so that it would add both datasources. 95th percentile calculation may be added to the 
new rrdtool though, I'm not sure..


-----Original Message-----
From: Todd A. Green [mailto:slartibartfast at awardsforfjords.com]
Sent: Friday, May 23, 2003 6:48 PM
To: rrd-list
Subject: [rrd-users] Partial data = no graph

I have two rrd files.

One which was being updated to a certain point then stopped (by choice).
The second starting being updated a short time later (by choice).

These represent a connection that was moved from one interface to

The problem is I can generate graphs on the data for the entire month
for data sources in either file.  I can also generate graphs with
different defs for each datasource in the two files into one graph.

However which I attempt to generate a combined datasource (CDEF) with
the two over the period which the first file wasn't updated I get no
graph.  I'm pretty sure at this point it's because the first file has
not been updated past a certain date.


Both files contain 1 month of 5 minute samples.

File 1 updated until March 19th 23:55.
File 2 starting updating on March 20th 00:35.

Here's a snatch of the RRD scripting
DEF:out1=/usr/local/bubba/data/mn/routers/cisco/c7206-1/interfaces/serial2_0/200303.rrd:out:LAST \
DEF:out0=/usr/local/bubba/data/mn/routers/cisco/c7206-1/interfaces/serial1_0/200303.rrd:out:LAST \
CDEF:out1_bits=out1,8,* \
CDEF:out0_bits=out0,8,* \
CDEF:out_bits=out0,out1,+,8,* \

out0_bits & out1_bits would generate a graph, but out_bits would not.

Any suggestions.  Only thing I can think of is to go back and update the
first file to the end of the month with NaN or 0.

BTW in looking through the archives I noticed mentions of 95th
percentile calcs.  That's one of the things my package was designed for.

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