Anyone know of a way of doing the following ?

what I want to do is essentually a network from of jbod raid

on the network is several workstations with various size hdd's the workstations only use a few gigs and all that space is waisted

what i would like to do is partition off say 80% of the drive on each workstation and merge all that space into a "single drive" basiclly a jbod raid.
it would need to be setup in such a way that if one of the workstations was off that it didnt worry the drive (say those files would just be "unavailable")

I have thought of using dfs but unless it can be setup as a single "share" that when 1 drive/partition is full to start on the next one automaticlly (unfortunatly my experence with dfs is very limited)

data security/backup is not required and if say one drive/partition was to completely dissapear only the files that were on it would become unavailable rather than the whole "raid" like it doe with jbod.

any ideas on a way / software to do this?