Once in a while, our server starts lagging. It always start around 6:00 ( GMT + 1) in the morning and ends around 3 till 4 hours later.

We have munin installed and we see a peak in CPU utilization and in the MySQL throughput. Below are some screenshots from munin.

Currently, we got no clue anymore how to find out what is causing this peak. It first looked like it happened every tuesday, but today the problem also arose.

We got a slight feeling it's something in MySQL since the throughput is so high. We checked if we had some cronjobs running and checked the slow logs query. None of them gave us an answer to what is causing this.

So, our question is how we can find out what the exact problem is. Or is there some sort of MySQL optimalization what is causing this?

We are currently running an Ubuntu 12.04.1 server

Thanks for your help!

CPU usage MYSQL Throughput Load averages

  • I'd start by looking in the mysql logs - IIRC, the general log doesn't record times when queries were run - but it also excludes a lot of other stuff for mysql APM - it's a much better idea to run with long_query_time=0 (although up till 5.something the minimum value was 1). The slow query log shows the queries being run (and time they were run at). – symcbean Jan 16 '13 at 15:40

My first, and probably one guess would have been a job running that is pegging the database around that time. Definitely no cronjobs running under another user is there?

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