[rrd-users] gap in graph in case of UNKNOWN value

[Martin T]

Simon,
sorry about late reply. So basically I guess something like this should work:


<<<<<
#!/bin/bash

#executes hddtemp and prints only the temperature number without units
temp=$(hddtemp -n /dev/sda)

#in case $temp string is empty, a "U" value is put to the database
if [ -n "$temp" ]
then
rrdtool update /home/martin/hdd.rrd N:$temp
else
rrdtool update /home/martin/hdd.rrd N:U
fi

>>>>>

Am I correct?

regards,
martin

2011/6/10 Simon Hobson <linux at thehobsons.co.uk>:
> Martin T wrote:
>
>>I'm sure it's showing zeros- when the network outage started, HDD
>>temperature value went from previous value directly to zero. If I had
>>a network outage and server was unreachable to a machine where
>>rrdtools runs, following data was written to RRD:
>>
>># rrdtool fetch HDD.rrd AVERAGE -s 1307061000 -e 1307075400
>>                          HDD
>>
>>1307061600: 2.8986899863e+01
>>1307062800: 0.0000000000e+00
>>1307064000: 0.0000000000e+00
>>1307065200: 0.0000000000e+00
>>1307066400: 0.0000000000e+00
>>1307067600: 0.0000000000e+00
>>1307068800: 0.0000000000e+00
>>1307070000: 0.0000000000e+00
>>1307071200: 0.0000000000e+00
>>1307072400: 0.0000000000e+00
>>1307073600: 0.0000000000e+00
>>1307074800: 1.0011661112e+01
>>1307076000: 3.3748035371e+01
>
> Yes, it's storing zeros.
>
>>If any additional information is needed, please ask!
>>
>>Am I correct, that in my case there are zeros written to the RRD in
>>case of UNKNOWN value? If yes, how to change this behavior?
>
> No, I can assure you that if you write unknown (or don't update at
> all) then you'll get unknown.
>
> So I'll refer you to a question I asked earlier :
>
>>  > Are you sure you are writing unknowns and not zeroes to the database
>>  > OR are not writing anything ?
>
> I suggest you need to look at your script and see what it's doing. My
> guess is that you are not correctly handing a lack of response - I
> think you must use the value "U" and not just an empty string. One
> useful technique is to add debugging statements and write data to a
> text file. For example, if your script had something like this :
>
> rrdtool update "${db_file}" "${timestamp}:${value}"
>
> then you coould change that to :
>
> rrdtool update "${db_file}" "${timestamp}:${value}"
> echo rrdtool update "${db_file}" "${timestamp}:${value}" >> "${debugfile}"
>
> Perhaps if you posted the relevant bits of your script ?
>
> --
> Simon Hobson
>
> Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
> author Gladys Hobson. Novels - poetry - short stories - ideal as
> Christmas stocking fillers. Some available as e-books.
>
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