Thanks of your reply guys, I dont really care the content of my data, cause I only had a few movies. I just want to know what is the cause of this happen. The condition of my NAS was fine. FTP running, BT running, and I mount my harddisk as standard due to there is only one 2TB hardisk installed. everything is running normally. And now I had a new problem, after I reformat, reboot, setup again, I put some movies into the NAS again, about 50GB, but when I login in by using the web locally, the capacity of hardisk indication remain the same. 1.78TB available total 1.78TB....I tried to do S.M.A.R.T test, it indicates pass.
please forgive my poor English