How can I analyse the level of harddisk access?

I don't know if this will help, but you can add a system monitor to a panel to monitor hard drive access (graph display).

Right click on a panel and "Add to panel", and from the list choose "System Monitor".

After that right click on System Monitor and configure what you want displayed.

I've been dealing with Conky recently, and I can recommend it.
For instance, these are some of the variables you can show:

diskio
    Displays current disk IO.

diskiograph (height),(width) (gradient colour 1) (gradient colour 2) (scale)
    Disk IO graph, colours defined in hex, minus the #. If scale is non-zero, it becomes the scale for the graph.

diskio_read
    Displays current disk IO for reads.

diskio_readgraph (height),(width) (gradient colour 1) (gradient colour 2) (scale)
    Disk IO graph for reads, colours defined in hex, minus the #. If scale is non-zero, it becomes the scale for the graph.

diskio_write
    Displays current disk IO for writes.

diskio_writegraph (height),(width) (gradient colour 1) (gradient colour 2) (scale)
    Disk IO graph for writes, colours defined in hex, minus the #. If scale is non-zero, it becomes the scale for the graph.

For more info: http://conky.sourceforge.net/

You can install it from the ubuntu repositories.

i myself use gkrellm2, a very neat program that can analyse pretty much all aspects of your system.

The functionality is exactly what I am after.
But is there a program which can do this without all this configurations?

Just output on the command line?

Maybe I should try to be more precicely:
I want to see by percentage the disk I/O processes sorted by the name of the programm. then I'd be able to know if it's firefox or openoffice or whatever which is keeping the harddsik that busy that I cannot do anything else.

Thanks.

I use conky... sudo apt-get install conky from a terminal installs conky... and More info about conky can be found by man conky command.. and http://conky.sourceforge.net/faq.html

run 'top' on the command line.

Hello,
since none of the answers offered here did satify me I used the following terms for another Google search:

"harddisk io stats by program linux "

I found a number of interesting programs which I rank here according how they match my needs here:

1) atop
http://www.atcomputing.nl/Tools/atop
Kind of advanced top which can interactively issue a command D to sort the processes by percentage of disk usage:
http://oldwww.atconsultancy.nl/atop/screenshots.html#dskoutpatch

=> Kernel needs to be patched for this kind of usage!

2) sysstat package
http://perso.orange.fr/sebastien.godard/documentation.html
A more general set of tools.

3) pio and topio
http://rootshell.be/~yong321/freeware/pio.html#mostuseful => only for Solaris and windows, the page explains why linux kernels aren't ready for such a task, yet.

Hope that this is also of help for others.