[rrd-users] Fetch with --resolution parameter

[Simon Hobson]

Leon Stringer wrote:

>And I query data with:
>
>   rrdtool fetch file.rrd MAX -r 86400 -s 1210766400 -e 1211371200
>
>So I read a value four times a day (every 21600s) and my resolution
>(-r) parameter is 4 * 21600 so I'm expecting one value for each day,
>i.e. seven values. The difference between start and end values is
>also a multiple of 86400. However, I get 29 values.
>
>Can anyone tell me what I'm doing wrong?


your start and end times are 7 days apart, 7x4 is 28, include both 
the start and end times and that makes 29. What you are doing wrong 
is not understanding what the tool is doing.

The resolution option merely tells fetch which existing RRA to use 
(in this case you are trying to select a non-existent RRA), it does 
NOT resample the data to some arbitrary step size.