To my experience samsung has a harddisk reliability problem for the popular 1Tb HD103UJ. See below for my experiences:
unreliable disk samsung HD103UJ
For warranty issue's, getting global support for IT equipment is a bit of a headache. Rule of thumb is that RMA's are only serviced in the area of purchase. See my experience in getting support on a SAMSUNG 2,5" harddisk out of it's warranty region.
Hard disk crash Samsung Spinpoint HM121HC
Unfortunately it's not good news - I stay away from samsung storage solutions for the time being,
Good luck!