We have a Western Digital Mybook World here (a Linux based NAS) which needs to be backed up now and then. The simplest way seemed to be hooking a USB disk of equal size to it and doing a diskcopy now and then. The theory seemed ok, practically it seems to work as well, with a huge downside: transfer rates are under 2MB/s. This is both using dd (preferred method)and cp, according to lsusb the USB bus is running at hispeed. It seems unrelated to the way I mount it (sync/async, whatever), as I tried dd when the drive wasn't mounted and the issue was still there. I also attempted to just use cp to a NTFS drive, installed ntfs-3g for this, ntfs-3g won't work at all though, and the default support is read-only.