2100 100% full = partial network no longer available errors

I have a Readynas 2100 (4.2.17) with 4x 3tb hdds which started misbehaving after it was inadvertently filled to 100% capacity (temporarily moving files from another NAS to work on that one). :oops: Once I realized that it was full, I found that directory access to some directories times out with the network name is no longer available error, which others can be accessed, but any attempt to delete a file ends up with the same network time out. I can however copy these files (which I've been doing), but without clearing some space, I can't seem to get at all the directories.

I can login to the admin pages, which although slow, mostly work - the principle exception being the share listing tab (which just hangs). I'm guessing that the lack of disk space is probably causing problems for the NAS, but I'm stumped at how to give it the space to work properly?

Any ideas are most welcome! (Not looking forward to attempting to copy off 8+Tb, even assuming I can get to all the directories to do so...)

Cheers, Limey.