My Synology has been anything but realiable in the past month or so. I've twice had to hard reboot it because it stops working. I think it stops writing all dat

My Synology has been anything but realiable in the past month or so. I've twice had to hard reboot it because it stops working. I think it stops writing all data, which means that even something as simepl as "echo "" > out" will hang forever. Can't even turn it off because DSM stops responding and "sudo reboot" hangs. I have no idea whether it's a disk going bad, the file system going bad or the entire device going bad. It did give a warning that an I/O command timed out on one of the disks, but I've yet to get a S.M.A.R.T. extended test completed on the disk.