Stefan --

The new 'amadmin holding list' command gives that sort of result.  If
you run, e.g., 

  amadmin DailySet1 holding list -l

It will give you a detailed listing; an example from my development box:

size (kB)  lv dump specification
172        0  knuth /tmp/amanda/prefix/etc 20070529
62         1  knuth /tmp/amanda/prefix/etc 20070529

'amadmin holding delete' can then be used to delete files from the
holding disk and update indexes appropriately, if you'd like.

Dustin

-- 
        Dustin J. Mitchell
        Storage Software Engineer, Zmanda, Inc.
        http://www.zmanda.com/