Pogoplug E02 - what is the little LED inside? (no replies)

I know what the large LED in the front is for - but what is the little LED inside the pogoplug E02 indicating?

See https://www.dropbox.com/s/bi0vwkaikasjp4e/LittleLED.jpg?dl=0 for an image of the little green LED.


Thanks,

Rainer