[rrd-users] Re: seek error in RRA

Hi Mark,

Let me tell you the background for this first.

I produce a set of graphs for a specific interval. Then i compare graphs
for different periods of time. In order to do this, I normalize the time
period.

I wrote a script to take a rrd and normalize it. Basically it copies the
definition from an rrd, creates a new rrd with the new time period and
updates the data with for a specific time range.

Since I need to keep the definition of the rrd the same, and it's
automated, it doesn't allow me to change the record length.

The definition of the original rrd is exactly the same but for one
difference, the beginning time.

If you remove the -b and the argument, you can see that it will work
fine.

Also, if you remove some of the data sources, it also work fine. (even
if you leave the -b untouched).

This is why I beleive it to be a bug.

As an addendum, I was using perl to parse the rrd, and I needed to see
that the completed rrd contains the appropriate data sources. I use
my ($names) = (RRDs::fetch("file","AVERAGE"))[2];

to find the names of them.

Since i'm only interested in the names, and not the data, the range I'm
fetching doesn't matter. I found that if I use:

my ($names) = (RRDs::fetch("file", 'AVERAGE','-s',315532801,'-e',315532851))[2];

I could circumvent the seek error (it doesn't give one if I specify the
range). It seems to be me it's a time issue more than anything.

Btw, I'm normalizing to 1980, as I took over some work from someone
else, and this is how they were doing it.

db

On Thu, Feb 24, 2005 at 08:05:27AM +0000, Mark Lawrence wrote:
> Hi Daniel,
>
> > rrdtool create test.rrd -b 315532801 -s 30 DS:wrqm_s:GAUGE:300:U:U
>
> You specify here a step size of 30 seconds.
>
> > DS:r_s:GAUGE:300:U:U DS:w_s:GAUGE:300:U:U DS:rsec_s:GAUGE:300:U:U
> > DS:wsec_s:GAUGE:300:U:U DS:rkB_s:GAUGE:300:U:U DS:wkB_s:GAUGE:300:U:U
> > DS:avgrq_sz:GAUGE:300:U:U DS:avgqu_sz:GAUGE:300:U:U
> > DS:await:GAUGE:300:U:U DS:svctm:GAUGE:300:U:U RRA:AVERAGE:0.5:1:1440
>
> And you have here a single RRA with 1440 data points spaced 1 step size
> apart (30 seconds). 1140 data points 30 seconds apart holds a maximum
> history of 43200 seconds.
>
> By default rrdfetch or rrdgraph uses the previous 24 hours worth of data
> which is 86400 seconds. So I suspect it is looking for data which is not
> simply not there.
>
> I bet if you increased the number of points stored in the RRA to 2880 (or
> maybe 2881?) it will work for you.
>
> Regards,
> Mark.
> --
> Mark Lawrence
>
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