[rrd-users] Re: fetch & resolution
mattb at hive.54.org
Sun Apr 29 12:08:19 MEST 2001
On Sun, 29 Apr 2001, Alex van den Bogaerdt wrote:
> Matthew Bostwick wrote:
> > However, I think you and I were talking about different things.
> no we're not. There is no such limit.
> > I was refering to the rrdtool fetch program not as to the database
> > limitations. After reading your above comments, it seems pretty
> > clear that there are fetch limitations. If there weren't
> There is no such limit. There probably is *some* limit but it is
> not anywhere near 600 rows.
> > limitations, the fetch commands bellow would work, right? Here's a snip
> > of some stuff we talked about before... I was talking about the same
> > subject.
> > > You try to fetch (988441200-986112000)/300 = 7764 rows. How many rows
> > > does your database have for the 5-minute RRA ? Suppose you only have
> How many rows does your database have for the 5-minute RRA ? 600?
> If you have only 600 rows, *you* *cannot* *fetch* *more* *rows*.
> > > 600 rows (the default if you use MRTG-like RRDs), you can only ask for
> > > 600*300 = 180000 seconds worth of data in a 300-second resolution.
> > > Any more and RRDtool will automatically override your resolution
> You can only query if it's in the database. If it is not in the
> desired RRA, the RRDtool programs (including but not limited to fetch)
> will use another RRA. This *is* what's happening to you. This is
> not a fetch problem, it is no problem at all. The limitation is in
> the database itself. Not in the program, in the database. This is
> user defined.
> > > No offence, but creating yet another webpage which isn't read anyway
> > > is the last thing I'm going to do. From the rrdtool manual page:
> And this is where I get lost. The snippet I included talked about
> just what you don't understand. You deleted it ?!?
Thanks for spending some time today with me. Here's that snipit of logic
you sent earlier.
"It works like this: If you want to store 1000 values
in 5 minute interval, rrdtool will allocate space
for 1000 data values and a header area."
"This automatically limits the history to the last 1000 values."
Okay, here's a dumb question. How do I figure out how many rows there
are in a give rrd data file? It doesn't seem like I can dump by row, but
just by date. Heck I'd dump all and stick it into an array, if I could do
Thanks for helping me out. I guess I was clueless all along while writing
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