USB auto-mounting lighting considerations

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USB device detection method is UUID (Unversally unique identifier) as a USB storage(disk) identifier, This method can surely distinguish and identify a general USB disk with USB 3G dongle storage, even it is a USB printer, in theoretics and in practice,
In short, when any USB device( a USB disk, 3G/4G dongle, printer ) is inserting, just only two detecting states will occur, one is mounted successfully, and the second is  mounting failure. In the UUID identifying method, we just have two conditions:

Ø   Case I: If it is “mount successfully”, then it means the USB device is a  disk (storage) only, it is impossible a 3G/4G dongle, even a printer

Ø   Case II: If it is "mounting failure", then it means the USB device is a unrecognized or unsupported device.

Ø   Case III: If it is remove the USB disk from USB port, then the USB LED shall be turn off.

Attention:

USB LED ON/OFF doesn’t mean software meaning of “safe removal” for the USB disk