Sony PS4 update 4.50 beta is currently testing the external HDD support with waters. Sony announced that it gave external HDD support for the PS4 in the past days. This feature is part of the PS4 Update 4.50 release and was tested for problems.
A surveillance of HDD support on the Sony side is turning into a very annoying problem. PS4 update According to 4.50 beta users, external PS4 hardware support requires you to uninstall the HDD safely before entering the rest mode. Users can set the PS4 to stay in rest mode after a period of inactivity.
If you turn on your console again, you will be asked for a message telling you that the PS4 is turned off without properly removing the drive and the drive should now be repaired. Even if your USB power is set to on, the HDD will not be connected in the idle mode.