Unable to locate old data in rrd file

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maneeshkumarnp
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Joined: Mon Apr 13, 2015 7:24 am

Unable to locate old data in rrd file

Post by maneeshkumarnp »

Would like to understand the way the data is rolled up in rrd file.

ex: The yearly data (1 day average) is kept for 2 years, after completion of the 2 year will the data get purged and start a fresh collection . or it will keep old data and start truncating now - 2 years ?

Thanks and Regards
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TheWitness
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Re: Unable to locate old data in rrd file

Post by TheWitness »

The RRDfile format is a first in first out queue design. So as you insert rows, old rows roll off the stack. It's as simple as that.

In Cacti 1.0 and above we gave the ability to define custom ranges for each round robin archive. You may alter them afterwards using the rrd tool tune command however it will leave gaps in certain graphs depending upon which round robin archive you choose to update. Others on these forums have written utilities to fill those gaps with data. However we have not released a formal tool for doing so to date.
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maneeshkumarnp
Posts: 17
Joined: Mon Apr 13, 2015 7:24 am

Re: Unable to locate old data in rrd file

Post by maneeshkumarnp »

Thank you for the reply.

I do understand that the rrd is a round robin database and old data will be truncated as and when new data comes in

However in our scenario, all of a sudden the old data is completely purged and new collection started for a graph which is more than 2 years. I wanted know if there is any setting to change this behavior. We need to keep 2 years data from now.
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TheWitness
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Re: Unable to locate old data in rrd file

Post by TheWitness »

Yes there is, but you need to first understand how rrdtool works and then configure Cacti to keep the amount of data you want.
True understanding begins only when we realize how little we truly understand...

Life is an adventure, let yours begin with Cacti!

Author of dozens of Cacti plugins and customization's. Advocate of LAMP, MariaDB, IBM Spectrum LSF and the world of batch. Creator of IBM Spectrum RTM, author of quite a bit of unpublished work and most of Cacti's bugs.
_________________
Official Cacti Documentation
GitHub Repository with Supported Plugins
Percona Device Packages (no support)
Interesting Device Packages


For those wondering, I'm still here, but lost in the shadows. Yearning for less bugs. Who want's a Cacti 1.3/2.0? Streams anyone?
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