Why aren’t you using ionice yet??? « Fried CPU
Most intermediate-level Linux users have heard of, or know how to use, the nice command. Well, ionice is like nice for the disk.
The best usecase for using ionice to improve performance is when you need to do two classes of tasks at once: The ones that don’t use much disk IO but demand fast response, and the ones that do a LOT of disk IO but don’t need it done urgently.