Ubuntu crashes due to high IO load using CFQ scheduler

So I’ve just discovered an interesting issue with an Ubuntu 12.04 server crashing under high IO load.

It appears that the default IO scheduler (CFQ) can cause a complete system lockup when its getting flogged.

When this is combined with OCFS2 it can lead to OCFS2 rebooting the system due to fencing. This appears to be the solution: http://techtitbits.com/2010/04/get-rid-of-freeze-ups-during-disk-io-activity-in-ubuntu/

I’ve just changed two of my boxes to using deadline instead, will report back on how it works.

Last updated by David Hooton at September 20, 2013.