[rrd-users] Re: RRA definition

[PAUL WILLIAMSON]

>>> "Sunil Modi (IT)" <smodi at bordersgroupinc.com> 11/1/2004 11:54:05 AM
>>>
>How can I define an RRA to capture every second as opposed to every 5
minutes?
>
>Right now I do RRA:AVERAGE:0.5:1:576 (captures every 5 minutes for 48
hours)
>
>I want an RRA to capture every second for 24 hours.  Is that
possible?
>
>Thanks,
>
>Sunil Modi

You really don't want to use RRDTool then.  Don't forget that it 
"normalizes" the data, thus giving you potentially partially 
incorrect information.  Run a script through cron, from the 
command line or some other process if under windows.  RRDTool 
is not going to give (IMHO) inaccurate results.  I've run RRDTool 
in 1 second, 10 second, 30 second and 1 minute increments to 
compare data and graphs.  I did this a while ago, but the best 
option I came up with for graphing any time slice under 30 seconds 
was to run a script that read in data and output it to a log file, then

import this data right into RRDTool once an hour to control exactly 
the values of the data I wanted.  It was a long time ago, but I didn't

have the option of the potential for normalization, so I logged the 
data to a text file with the time, then once an hour I took this data,

made sure I had 3600 points, and shoved them into a one-second 
RRA.  I realize this may introduce errors, but I felt it was acceptable

rather than getting normalized data.

The lowest resolution I have in an RRA today is (I think) ten seconds. 

Even that introduces too much error, but it is what was requested.

Paul

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