[rrd-users] can't sanity-check rrdtool with sample data ... please help

Gore Jarold gore_jarold at yahoo.com
Wed Jun 27 04:47:32 CEST 2007

--- Alex van den Bogaerdt <alex at ergens.op.het.net>

> On Tue, Jun 26, 2007 at 02:34:19PM -0700, Gore
> Jarold wrote:
> > My question is simple:  How do I plug in 6 test
> values with 6 specific dates and successfully fetch
> them back out again _exactly as I entered them_ ?
> RRDtool behaviour is well documented.  You have
> selected a step
> size of 86400, so every timestamp is a whole
> multiple of 86400.

Yes, I see that it is - and that is good, but it's the
_wrong_ multiple of 86400 - the dates coming out of my
RRD are (as far as I can tell) random.

Look at my create statement:

rrdtool create hits.rrd --start 1141200000 --step
86400 DS:hits:GAUGE:172800:0:U RRA:MAX:0.5:1:3650

Notice how the --start is 1141200000  ?

Now look at my update statement - the first date is
+86400 after --start, and each subsequent date is
+86400 after the previous one:

rrdtool update hits.rrd 1141286400:1 1141372800:10
1141459200:10 1141545600:12 1141632000:12

So now look at the output of:

rrdtool fetch hits.rrd MAX --start 1141200000 --end

1141257600: 1.0000000000e+00
1141344000: 7.0000000000e+00
1141430400: 1.0000000000e+01
1141516800: 1.1333333333e+01
1141603200: 1.2000000000e+01
1141689600: 1.2000000000e+01

Hmm... how very odd ... NOT ONE of those dates is in
my 'rrdtool update' command.  Every single one of
those six dates above is _from nowhere_.  I didn't
start my RRD at any of those dates, and I have not
entered data for any of those dates.

So where did those dates come from ?  The fact that
they are all +86400 from each other is not useful when
they are not the data I entered...

(and this, of course, does not even mention the fact
that my data input was:

1, 10, 10, 12, 12, 12

and 'fetch' output:

1, 7, 10, 11.3, 12, 12

Yes, I have read the HOWTOs - as you can see all of my
command lines are just fine.  What I would like to
know is, how do I put in certain data and then get
that same data back out ?  As you can see I was not
able to here...

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