Most modern media does error checking, and usually error correction as well. This isn't primarily because the media is unreliable, although that is true. The ma

Most modern media does error checking, and usually error correction as well. This isn't primarily because the media is unreliable, although that is true. The main reason to do ECC is to increase the capacity of the media. Having ECC able to cope with a reasonable number of bit errors allows the bits to be crammed closer together on the media while still being reliable.