Use

find / -printf "%s\t%p\n" | perl heap
[download]

where heap is the perl program listed at the node Re: Re: Re: Re: Sorting values of nested hash refs.

The find prints all files together with sizes. The script uses a binary heap to select the 32 largest ones from it.

For more information, read its thread which is about a similar problem.

Update: on my system, this finds /proc/kcore as one of the largest files. You'll have to find out how not to include the /proc fliesystem in thesearch. Also, this will list hard links multiple times.