01 October 2009

Recently I got a report that some pages on the site were extremely slow. Looking at the web server metrics didn’t show anything new however mySQL DB metrics showed a definite change

MySQL server CPU utilization

ie. at the end of Week 38 there is an increase in CPU utilization. Nearly 60% increase. Interestingly enough there was a new software release at the end of Week 38 which pointed to either a bug or a new feature. Luckily I have been collecting mySQL metrics using this gmetric script. This led me to these two graphs

mysqlupdate

mysqlinsert

So nearly double number of inserts and nearly triple the updates. Using mysqlbinlog I analyzed the update and insert statements and was able to identify the two culprit INSERT and UPDATE statements then sent it off to developers.

I also observed that had I watched the binary log growth I may have identified this earlier since there were a lot more binary logs for the period since the release. Thus mysql average binary log growth rate gmetric was born :-). Now all I need to do is find out what normal growth rate is and if it goes outside of that norm use Nagios to send me a non-urgent alert.