High IO usage on Database server

If "iotop" shows that most resources are used by jbd2/md2-8 and not by mysql service,

try to add:

innodb_flush_method=O_DSYNC

to my.cnf [general] section and restart mysql service.

Source: http://dev.mysql.com/doc/refman/5.5/en/optimizing-innodb-diskio.html