All the sources I can find suggest that the meaning of the Run Out Cancel SMART attribute (#203) is "Number of ECC errors". http://en.wikipedia.org/wiki/S.M.A.R.T.#Known_ATA_S.M.A.R.T._attributes This makes no sense to me. Runout is a measure of eccentricity. Therefore I would think that run out cancel should reflect the amplitude of the sinusoidal error signal required to be injected into the voice coil servo loop to compensate for any eccentricity in the track, assuming that's how it's done. I wonder if someone originally misinterpreted ECCentricity error (?) as ECC error, and perhaps the mistake has been propagated without challenge??? - Franc Zabkar -- Please remove one 'i' from my address when replying by email.