[rrd-users] Changing data collection rate in an existing file

Steve Shipway s.shipway at auckland.ac.nz
Thu Apr 12 01:36:33 CEST 2012

This is very awkward to do.  You'd need to dump the RRD to XML, modify the
XML, then reload it to make a new RRD file with the different step size.


Your 5-min 1-sample RRAs would need to be changed to 5-min 5-sample, and
similarly for the larger RRAs.  You'd likely also need to create a new 1-min
1-sample RRA, 3 months long, and initially populate it with data pulled from
the 5-min RRA.


This would be possible, but (a) you wouldn't have the data granularity for
historical data, and if you miss out the initial copy of data from the
original 5min RRA to the new 1min RRA you'd get odd behaviour, and (b) you
would need to write a fairly complex program to process the XML, as no
existing utility I know about can do this.





Steve Shipway

ITS Unix Services Design Lead

University of Auckland, New Zealand

Floor 1, 58 Symonds Street, Auckland

Phone: +64 (0)9 3737599 ext 86487

DDI: +64 (0)9 924 6487

Mobile: +64 (0)21 753 189

Email:  <mailto:s.shipway at auckland.ac.nz> s.shipway at auckland.ac.nz

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From: rrd-users-bounces+s.shipway=auckland.ac.nz at lists.oetiker.ch
[mailto:rrd-users-bounces+s.shipway=auckland.ac.nz at lists.oetiker.ch] On
Behalf Of Brent Barr
Sent: Thursday, 12 April 2012 6:38 a.m.
To: rrd-users at lists.oetiker.ch
Subject: [rrd-users] Changing data collection rate in an existing file


I have over a year of data for my systems at a 5 minute sample rate. I'd
like to change to collecting data every minute, but would rather not end up
with new rrd files where I have a before/after problem when I'm charting

My problem is that if I am collecting data every minute, I want to collect
and store 5x the data too so I still have the high accuracy data for three
months.  So I can't just change the step size in the .xml dump and restore
it, I think I'd have to make some serious changes to the database file too.

Or is there a way to move data from one file to another?  I have another rrd
setup with the correct step and enough locations for the faster collection
rate. Can I grab the data from the old file and drop it in the new one
somehow?  Maybe using the fetch and update commands and a loop?

Thanks for any help-

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