ionice. Only that made upgrading worth it.

Copying gigabytes of disk can get the system sluggish. On Linux, the solution is so simple. If process 18898 happens to take control of your disk, just go:

ionice -c 3 -p 18898

And you have your computer back. “-c 3″ means class 3, which is idle class. In other words, take the disk when nobody else asks for it.

I love it. More here.