[drraw-users] Why is granularity 30 minutes?

[David Nolan]

Kevin,

You're only keeping 288 samples in the 5 minute RRA, which is exactly
24 hours worth.  But it looks like you're trying to graph 30 hours
worth of data.  RRDTool will only use a single RRA as the data source
for a single graph.   If you try to graph 24 hours or less of data you
should get more granularity.

My suggestion would be to store more datapoints in your 5 minute RRA
if you want to see more precise graphs for a period longer then 24
hours.  Either 36 or 48 hours should be good.

-David

On Thu, Oct 30, 2008 at 9:41 AM, Zembower, Kevin <kzembowe at jhuccp.org> wrote:
> I don't understand something regarding drraw (version SVN-SNAPSHOT [1526 post 2.2b1]). I have an RRD created by this script:
>
> kevinz at centernet:/usr/local/src/rrd$ cat createinboundlatency
> #! /bin/sh
>
> #Creates an RRD for recording inbound web page latency to http://www.jhuccp.org/ from various hosts
>
> #Read every five minutes
> #Average one reading every 5 minutes and store 24 hours
> #Average 5 readings (30 min) and store 1 week
> #Average 24 readings (2 hr) and store 31 days
> #Average 288 readings (24 hr) and store 1 year
> #Average 2016 readings (1 wk) and store 5 years
> rrdtool create /var/log/rrd/inlatency.rrd \
>  --start ` date +"%s"`  \
>  --step 300             \
>  DS:dailyrazor:GAUGE:600:0:U \
>  RRA:AVERAGE:0.5:1:288  \
>  RRA:AVERAGE:0.5:6:84  \
>  RRA:AVERAGE:0.5:24:372  \
>  RRA:AVERAGE:0.5:288:365 \
>  RRA:AVERAGE:0.5:2016:260
>
> kevinz at centernet:/usr/local/src/rrd$
>
> I update this RRD every 5 minutes. However, my highest granularity graph in drraw seems to aggregate the data into 30 minute averages (see the attached image).
>
> Is this the correct behavior of drraw? Is there any way to change it to display the full granularity that the RRD is capable of?
>
> Thanks so much for your advice and suggestions.
>
> -Kevin
>
> Kevin Zembower
> Internet Services Group manager
> Center for Communication Programs
> Bloomberg School of Public Health
> Johns Hopkins University
> 111 Market Place, Suite 310
> Baltimore, Maryland  21202
> 410-659-6139
>
>
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