[rrd-users] XML dump/restore: How to handle "cdp_prep"?

Christian Schrötter rrdtool at lists.kb19.at
Sun Aug 17 11:20:49 CEST 2014

Sorry Alex, forgot the list as recipient... ;-)

>> * GROW each RRA like rrdresize by a new format definition.
> Explain "by a new format definition".

1st step: Only more rows in the past (like rrdresize):
  * RRA 0/1/2: 576 rows -> 1584 rows (+1008 rows at the beginning)
  * RRA 3/4/5: xxx rows -> xxxx rows (+xxx rows at the beginning)
  * ...

>> * Import old (deleted) data from another (dumped) RRD file.
>> This works great, but I'm not sure what to do with the "cdp_prep" 
>> XML node, especially with the *value elements. Am I supposed to leave 
>> it unchanged (the rrdresize way), delete the whole node or change it 
>> to another value?
> Rrdtool resize adds rows to the past of the data. It does not do
> anything with the present time where the current CDP is being built.
> If your version is doing something to the data (e.g. change amount of
> time per CDP) then you should change cdp_prep accordingly.  If not,
> not.

2nd step: Import some data into the added rows. The current rows (= 
existing ones) are not touched. Is this problematic too?

> If you don't know how CDPs are built, may I suggest you visit my site
> ( http://rrdtool.vandenbogaerdt.nl ) and also look in the source code
> of rrdtool.

Thanks, I'll take a look at this too.

With kind regards,
Christian Schrötter

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