What is Power_On_Hours (ID 9)?

What is Power_On_Hours (ID 9)?

• A. Number of power cycles per day.
• B. Temperature reading.
• C. Total drive uptime; not a fault by itself.
• D. Encryption status.

Answer: (C)

Power_On_Hours is a SMART attribute that tracks how long the drive has been powered on. It counts the total hours of uptime, so it reflects how long the drive has been operating since it was manufactured (not a fault or error indicator). This value grows as the drive stays on, and it’s useful for estimating age or wear when considered alongside other SMART data. The other ideas describe different metrics: the number of power cycles per day would come from a counter of on/off events; a temperature reading comes from a temperature sensor; encryption status is a separate property. So Power_On_Hours represents total drive uptime in hours, not a fault by itself.

Power_On_Hours is a SMART attribute that tracks how long the drive has been powered on. It counts the total hours of uptime, so it reflects how long the drive has been operating since it was manufactured (not a fault or error indicator). This value grows as the drive stays on, and it’s useful for estimating age or wear when considered alongside other SMART data. The other ideas describe different metrics: the number of power cycles per day would come from a counter of on/off events; a temperature reading comes from a temperature sensor; encryption status is a separate property. So Power_On_Hours represents total drive uptime in hours, not a fault by itself.