Is there a way to prioritize disk operations ?

[Yuri]

Currently one can set nice value to the process. But it only affects the 
CPU scheduling, so if this process is CPU bound it would yield to others.
What if the process is disk-bound, like some backup operations? The 
backup copying large disk seriously affects performance of all other 
apps accessing the same disk.

Is there a way to set the priority value on the process for the disk 
operations, so that all disk operations originating from the process 
will be scheduled in similar way how CPU is scheduled based on the nice 
value of the process? The disk-intense backup process with low disk 
priority won't affect the other processes at all.

Yuri