pls see answer below. thanks.
Note: the only time the internal drive is also gonna be affected is after every File copy that I perform on the NMT itself and on that file copy the internal HDD is involved.
hmm, affected when copying... does it happen even if it prompts "copy completed"? id understand if power off midway.
IMO, sa externals and bare seems an sync;sync; in their powerdown sequence is needed. plus a force dismount(i.e. if a file/node/folder is open, it unmounts it by force and flush the cache) would do it.
as to the copying, if it copy completes, then the release of the fs volume remains in use, despite completion.
i am guessing at this point, from an OS' fs view.