Nice stuff.   There is some interesting reading here on tuning dirty writes - https://code.google.com/p/epicnms/wiki/Scaling

From: Markus Klock <markus@best-practice.se>
Reply-To: Observium <observium@observium.org>
Date: Friday, 24 October 2014 7:57 am
To: Observium <observium@observium.org>
Subject: [Observium] Reduce your storage IO with rrdcached

There was some discussion on IRC the other day about rrdcached and how it can be used with Observium to reduce your storage IO a lot when polling a huge amount of interfaces.
However, not a lot of documentation exists yet on how to get rrdcached to work with observium. I did some trial and error and found a working method and wrote a quick and dirty guide.
You can find it here: http://blog.best-practice.se/2014/10/using-rrdcached-with-observium.html
Feedback is highly appreciated!

/Markus