[rrd-users] Fup: About logging the REAL value

Alex van den Bogaerdt alex at ergens.op.HET.NET
Wed Aug 23 13:45:00 MEST 2000


At least there is some discussion now.  This is good, no matter if a
change is implemented or not.

Now for the original problem:

Some room, some entry, somehow you *know* in and out going traffic can
only happen once every minute.  However, you do not know when this can
happen, it can be anywhere in this minute.

A database is created.  As soon as a change is detected, the RRD is
updated.  The current time is used, not the available workaround.
12:01:20 a person enters the room.  I know, for sure, that the amount
of people in the room alters from 4 to 5.  What happens in the RRD?
The previous interval (presumably going from 12:00 to 12:01) is updated
and the current value is remembered for the next update.  This update
happens at, for instance 12:02:20.  Another person enters the room and
the number of people in the room is 6.  I *know* the minimum and maximum
without doing any guessing, without being inaccurate.  Averaging *does*
introduce an error here.

If I store the number of people this way, I strongly feel that RRDtool
should store the value 5 at 12:02:00.000, not 5.xx  To implement this
without breaking current and expected behaviour, a new DST must be

I have no objection against this averaging when counters are involved.
gauges are not counters.

Perhaps I don't see the obvious solution to the problem and presented
a less obvious solution.  If so, enlighten me :)

 / alex at slot.hollandcasino.nl                  alex at ergens.op.het.net \
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| http://faq.mrtg.org/                                                 |
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