Linux disk IO load breakdown, by filesystem path and/or process?

Does anyone have experience with a tool that can provide an indication of disk IO load by filesystem path.

I use to 'iostat' utility, frequently, to learn how much disk activity is taking place on a Linux host. 'iostat' provides a per-device breakdown, so you can see activity on a particular block device. But it doesn't go any deeper than that--you can't, for instance, query the write load generated by 'httpd' in the directory '/var/log/httpd/'.

You can use iotop for that purpose.

I works like normal top, I cannot say much more. Most distributions will have it packaged, but here is its homepage. You will need a recent kernel.

Using htop do the following.

htop
F5 (Tree view)
F2 (Setup)
Select columns
Select RBYTES WBYTES
F10 (Done)

And there you go, per process disk I/O, in real time.