I use driver 5.1.4b for a long time. It works fine, but I don’t recommend you to use “Fsys -a”, use “Fsys”.
I already have 3 DOCs with destroyes filesystem (first 3-4kb filled with “0”). I tried to kill filesystem on it recently by filling DOC with files till end and trying to write more when it doesn’t have any free space. I had several successful attemps (I killed it ) with “Fsys -a”. Without “-a” I can’t kill it.