Attribute ID: 9 (0x09)
Hard drives, supporting this attribute
Samsung, Seagate, IBM (Hitachi), Fujitsu, Maxtor, Western Digital
Power-On Hours (POH) S.M.A.R.T. parameter indicates a count of hours in power-on state. The value of this attribute shows total count of hours (or minutes, or seconds, depending on manufacturer) in power-on state. A decrease of this attribute value to the critical level (threshold) indicates a decrease of the MTBF (Mean Time Between Failures).
This parameter is considered informational by the most hardware vendors. Although degradation of this parameter can be an indicator of drive aging and/or potential electromechanical problems, it does not directly indicate imminent drive failure. Regular backup is recommended. Pay closer attention to other parameters and overall drive health.
See also: S.M.A.R.T. Monitoring.