Updating existing RRAs/RRDs to retain more data over time

[cjlove72]

Hello,

I've just been searching the forums on how to modify our existing RRD files to contain more granular data over time.

I discovered the HOWTO regarding extending RRAs within RRDs (http://forums.cacti.net/viewtopic.php?t=11425) and understand that the resize script can be used to resize the RRAs within the RRDs to add extra data points, but what I'm not clear on is how this relates to the Cacti definiton of the RRA?

For example, if I wanted to keep 10 minute averages for the monthly view instead of the default 2 hour averages, would I need to modify the related RRA that's defined for the Data Source, e.g. Monthly (2 Hour Average) to reduce the number of steps and increase the number of rows? I.e. the Monthly (2 Hour Average) RRA contains the following settings:-

Steps : 24
Rows : 775
Timespan : 2678400

So if I wanted to change this to retain data at 10 minute intervals, should I modify it as follows:-

Steps : 2
Rows : 9300
Timespan : 2678400

Then would I use the resize script to add an additional 9000 rows into the Monthly RRA within the RRD files using my data sources?

Would Cacti then start populating the RRAs with consolidation occuring based on the new RRA settings (i.e. 10 minutes instead of 2 hours)?

I have also seen the HOWTO post (http://forums.cacti.net/viewtopic.php?t=9605) that describes how to create a single RRA containing yearly stats at 5 minute intervals, but I'd rather not have to recreate all our Data Templates, Graph Templates and ulitmately RRDs as we have several months of data stored for a few hundred devices, with multiple weathermaps also referencing all of these RRDs. The effort required to regenerate all of these Weathermaps using 1000's new RRD files would be enormous.

Space is not an issue for the larger RRDs containing more data, as the Cacti repository resides on our SAN.

Sorry if this sounds like I'm confused...that's because I am!

Cheers,

Chris

[gandalf]

Please see 1st link of my sig. Select the rrdtool chapter. There's a complete description of resizing rrdtool files
Reinhard