Black Hole
May contain traces of nut
OK, so I was being a bit loose with my use of "unhealthy" (poetic licence).
This has come up in several topics so let me make a definitive statement:
A USB 2.0 or USB 3.0 (with USB 2.0 fall-back) drive with separate power supply (usually called "External") will be fine, it draws little or no power from the USB interface but has the inconvenience of finding an extra mains socket.
A USB 2.0 drive that is powered from the USB port (usually called "Portable") will usually be OK; the USB 2.0 specification permits a device to draw up to 500mA, and a properly designed port will be able to supply that. Some drives used to be provided with a double plug lead so as to take power from two ports - this is not an option with the HD-FOX, and awkward with the HDR-FOX, but is not common these days. I currently have two 500GB USB2 drives connected (and functional!) to my HDR-FOX.
A USB 3.0 drive will have a fall-back mode that communicates with a USB 2.0 port. However, the specification permits a USB 3.0 device to draw up to 900mA and this exceeds the rated capability of the HD/HDR-FOX's ports. This is not to say that such a device will draw more that 500mA, just that it could and still be within specification, therefore you would have no comeback. It is entirely possible that a drive designed for a USB 3.0 port is not fitted with a socket for an external supply, and not provided with an external wall wart.
The effect of drawing too much current from the USB port will be mis-operation of the drive and possible mis-operation of the HD/HDR-FOX. It should not lead to damage in either (if properly designed).
Please note that manufacturers reserve the right to change specification without notice, so while it might be shown that a particular make and model of USB 3.0 drive works with an HD/HDR-FOX, it is likely but not certain that another one of the same model will also work, and the slight variations between HD/HDR-FOXs could stop the same device working on a different HD/HDR-FOX. These are the sorts of thing that happen when taking a risk outside specification. A way to side-step this is to use an external powered driverless USB hub (preferably USB3).
It is for those reasons that I personally would avoid a USB3 drive if faced with the choice, especially as I have no computers fitted with USB3 ports to take advantage of the fast transfer rates. If you have a computer with a USB3 interface and are likely to want to transfer data from/to the drive you might be tempted and consider the (slight) risk acceptable - but note that the transfers between the drive and the Humax will only go at Humax speed. The risk balance will change as the industry shifts to USB3, and USB2 portable drives become difficult to obtain.
This has come up in several topics so let me make a definitive statement:
A USB 2.0 or USB 3.0 (with USB 2.0 fall-back) drive with separate power supply (usually called "External") will be fine, it draws little or no power from the USB interface but has the inconvenience of finding an extra mains socket.
A USB 2.0 drive that is powered from the USB port (usually called "Portable") will usually be OK; the USB 2.0 specification permits a device to draw up to 500mA, and a properly designed port will be able to supply that. Some drives used to be provided with a double plug lead so as to take power from two ports - this is not an option with the HD-FOX, and awkward with the HDR-FOX, but is not common these days. I currently have two 500GB USB2 drives connected (and functional!) to my HDR-FOX.
A USB 3.0 drive will have a fall-back mode that communicates with a USB 2.0 port. However, the specification permits a USB 3.0 device to draw up to 900mA and this exceeds the rated capability of the HD/HDR-FOX's ports. This is not to say that such a device will draw more that 500mA, just that it could and still be within specification, therefore you would have no comeback. It is entirely possible that a drive designed for a USB 3.0 port is not fitted with a socket for an external supply, and not provided with an external wall wart.
The effect of drawing too much current from the USB port will be mis-operation of the drive and possible mis-operation of the HD/HDR-FOX. It should not lead to damage in either (if properly designed).
Please note that manufacturers reserve the right to change specification without notice, so while it might be shown that a particular make and model of USB 3.0 drive works with an HD/HDR-FOX, it is likely but not certain that another one of the same model will also work, and the slight variations between HD/HDR-FOXs could stop the same device working on a different HD/HDR-FOX. These are the sorts of thing that happen when taking a risk outside specification. A way to side-step this is to use an external powered driverless USB hub (preferably USB3).
It is for those reasons that I personally would avoid a USB3 drive if faced with the choice, especially as I have no computers fitted with USB3 ports to take advantage of the fast transfer rates. If you have a computer with a USB3 interface and are likely to want to transfer data from/to the drive you might be tempted and consider the (slight) risk acceptable - but note that the transfers between the drive and the Humax will only go at Humax speed. The risk balance will change as the industry shifts to USB3, and USB2 portable drives become difficult to obtain.