I’ve already written about changing the I/O scheduler for hard disk under Linux and avoiding sudden outburst of disk I/O using ionice utility. Google has sponsored Gelato@UNSW to take a close look at the disk schedulers in Linux, particularly when combined with RAID. They have now published their findings.
A sudden outburst of violent disk I/O activity can bring down your email or web server. Usually, a web / mysql or mail server serving millions and millions pages per months are prone to this kind of problem. Backup activity can increase current system load. To avoid this kind of sudden outburst problem, run your script with scheduling class and priority. Linux comes with various utilities to manage this kind of madness.