Heh, zrovna vcera jsem dostal od naseho testing tymu informaci k TS256GSSD420K:

There is one observation to make: Power_On_Hours attribute is not conform to reality.
e.g.: from Jul 6 19:00:39 until Jul 7 07:30:50 there are 12 hours 30 min, but Power_On_Hours increased only with 4:

Device Model: TS256GSSD420K
Firmware Version: O0918B