[rrd-users] Minimum resolution for fetching data

Discussion:

(too old to reply)

Martijn Lievaart

2014-07-31 08:59:47 UTC

Hello list,

I googled this but could not come up with anything definitive, so I
thought I'ld ask here.

I work for a client that uses Citrix a lot. This means that it sometimes
is important to get graphs in one second resolution. I cannot seem to
get rrdtool to do so, the minimum resolution it will come up with is 1
minute.

My question, is this my mistake somehow, or is this RRD design? If
needed I'll post details about how I create the RRDs and how I fill them.

Regards,
Martijn Lievaart

Steve Shipway

2014-07-31 09:07:27 UTC

Permalink

The minimum resolution you can fetch is the minimum resolution of all the RRAs which completely cover the time window you are asking for.

The minimum resolution of an RRA is 1 interval, and the minimum interval is 1 second. Both of these are set at RRD creation time, and have an implication on data collection and update frequency.

If you are only getting 1 minute resolution data, I suspect you have a 1minute Interval on your RRD with a count-1 RRA.

Steve

Steve Shipway
University of Auckland ITS
UNIX Systems Design Lead
***@auckland.ac.nz
Ph: +64 9 373 7599 ext 86487

________________________________________
From: rrd-users-bounces+s.shipway=***@lists.oetiker.ch [rrd-users-bounces+s.shipway=***@lists.oetiker.ch] on behalf of Martijn Lievaart [***@rtij.nl]
Sent: Thursday, 31 July 2014 8:59 p.m.
To: rrd-***@lists.oetiker.ch
Subject: [rrd-users] Minimum resolution for fetching data

Hello list,

I googled this but could not come up with anything definitive, so I
thought I'ld ask here.

I work for a client that uses Citrix a lot. This means that it sometimes
is important to get graphs in one second resolution. I cannot seem to
get rrdtool to do so, the minimum resolution it will come up with is 1
minute.

My question, is this my mistake somehow, or is this RRD design? If
needed I'll post details about how I create the RRDs and how I fill them.

Regards,
Martijn Lievaart

Martijn Lievaart

2014-07-31 09:18:13 UTC

Permalink

OK, thanks.

I must be doing something wrong then. I'll triple check and post either
the solution or a followup question.

Martijn Lievaart

Post by Steve Shipway
The minimum resolution you can fetch is the minimum resolution of all the RRAs which completely cover the time window you are asking for.
The minimum resolution of an RRA is 1 interval, and the minimum interval is 1 second. Both of these are set at RRD creation time, and have an implication on data collection and update frequency.
If you are only getting 1 minute resolution data, I suspect you have a 1minute Interval on your RRD with a count-1 RRA.
Steve
Steve Shipway
University of Auckland ITS
UNIX Systems Design Lead
Ph: +64 9 373 7599 ext 86487
________________________________________
Sent: Thursday, 31 July 2014 8:59 p.m.
Subject: [rrd-users] Minimum resolution for fetching data
Hello list,
I googled this but could not come up with anything definitive, so I
thought I'ld ask here.
I work for a client that uses Citrix a lot. This means that it sometimes
is important to get graphs in one second resolution. I cannot seem to
get rrdtool to do so, the minimum resolution it will come up with is 1
minute.
My question, is this my mistake somehow, or is this RRD design? If
needed I'll post details about how I create the RRDs and how I fill them.
Regards,
Martijn Lievaart
_______________________________________________
rrd-users mailing list
https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users

Martijn Lievaart

2014-07-31 10:26:28 UTC

Permalink

Duh!

My 1 second RRA wasn't large enough to cover the time period I looked
at. I'll try in a minute, but that is definitely wrong.

And yes, I'm really getting (most of the) updates one per second. The
program that generates the data by parsing libpcap output makes sure of
that. I'm currently only testing with pre existing captures (hence it
was so far in the past I did not have 1 second resolution data) but when
it looks at life data there will be a queueing mechanism to ensure the
data gets delivered.

Thanks again,
Martijn Lievaart

Other possibilities are that you're not getting the smaller RRA because it doesnt completely cover your time window, or because it has the wrong CF, or you have a 1sec interval but only a 1 minute RRA.
If you set a RRD with a 1second interval, you probably want a much higher heartbeat on the various DSs, plus a very small XFF on the RRA, unless you really are getting your updates one per second.
Steve
Steve Shipway
University of Auckland ITS
UNIX Systems Design Lead
Ph: +64 9 373 7599 ext 86487
________________________________________
Sent: Thursday, 31 July 2014 9:18 p.m.
Subject: Re: [rrd-users] Minimum resolution for fetching data
OK, thanks.
I must be doing something wrong then. I'll triple check and post either
the solution or a followup question.
Martijn Lievaart