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Entry type: FAQ Entry ID: 24510106, Entry date: 01/31/2007

What factors affect the service life of ATA hard disks and what does the MTBF value mean?

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Configuration Notes:
Hard disks are sensitive electromechanical products whose reliability is greatly influenced by their surroundings and environment. Alongside relative humidity, power fluctuations or failure, shocks and vibrations, it is above all high temperatures that are a frequent cause of hard disk faults. The reliability of the electronics and mechanics - spindle motor and bearing - depends heavily on it. Inadmissible operating environments (e.g. exceeding of temperature ranges or insufficient protection against vibrations with commercially available PC housings) are a major reason for hard disk failure as proven in independent tests.

MTBF value of ATA hard disks:
The MTBF value (Mean Time Between Failure) is a measure of the reliability of hard disks. It gives the average time to be expected between two failures and is an indication of the failure probability. The MTBF value depends on the following factors:

  • Utilization time POH (power on hours) per month
  • Load of the hard disk duty cycle (read/write cycle depending on the application)
  • Environmental conditions of operation (e.g. temperature, humidity, vibration and shock).


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