all iPod (4th generation) have had disk defects（・・？

is all the hard disk of iPod (4th generation) is full of defects（・・？

when i bought a new one, its HD failed, then applecare changed the one for me was also corrupted data and failed eventually.

meanwhile, my another iPod of the previous older version is still alive till now, as well as the 5th generation one.

three of them I only needed to replace the defective 4th generation.

even so I could claim nothing from Apple yet !