1) bug: if in "Network Share Settings" the option "oplocks" is enabled, the hard-disk drives will never go into hibernation. To avoid this problem, either "oplocks" should be disabled, or NFS service should be enabled (in this way it automatically disables all "oplocks").
2) P2P's poor integration with HDD hibernation: Even I set "Stop seeding after - 1 minute" or if I set "Stop seeding when meet - 100%", and the torrent has finished to be downloaded, I've noted that P2P still continues to seed. Due to the fact that I want hard-disks have to go into hibernation after n minutes, they will never go into hibernation if torrent continues to be seeded. The only way to stop seeds (and to let hdds go into hibernation) is to disable P2P!!! P2P should be better integrated (or even be part of the DNS325 firmware and not a plugin anymore) in order to stop itself when all P2P downloads are finished and to let hdds go into power-saving mode if required.
3) Consider the situation if the HDDs are already into hibernation, and I want to power-off the NAS. I press the power button (or I select shutdown in web management). What's happen? The HDDs wake up (you hear the sound of their engine again)... and then are powered off!!!! It's a waste of power and reduces the life of HDDs!!! Is it a bug or a needed behavior?