SMART values and there meaning HDD diskinfo

Summary:

This article list the most important HDD S.M.A.R.T. values and their meaning.

Resolution:

The following list shows the most important HDD S.M.A.R.T. values and their meaning

• Seek Error Rate: Counts the uncorrectable errors during read operations. This is an indication of a possible problem when positioning the read/write head.
• Raw Read Error Rate:Non-correctable errors in the read operation. This is an indication of a possible problem with the disk surface(s).
• Scan Error Rate:Non-correctable errors when checking the disk surface. The RAW value <> zero increases the probability of failure tenfold.
• Througput Performance:General value for the data throughput. A low value indicates a problem.
• Spin Up Time:Average start time of the disk motor. A bad value could indicate bearing problems of the motor or the disks.
• Reallocated Sector Count:Counts how many spare sectors the disk drive has used. The non-zero RAW value quintuples the probability of failure.
• Drive Temperature:The current (unfortunately mostly very inaccurate) temperature of the drive. Additionally the maximum and minimum value is stored. The probability of failure increases from a temperature of 55° Celsius. Some drives sometimes show temperatures below the ambient temperature. An external temperature measurement is preferable.
• UltraDMA CRC Error Rate:Number of CRC checksum errors during data transmission. May also indicate defective cables, a driver conflict or overclocking problems.
• Seek Time Performance:General value indicating the performance of the read heads. Low values may be an indication of a mechanical problem.
• Spin Retry Count:The counter that logs how many times the motor has had to start for the disk to reach its typical operating speed.
• Recalibration Retries:The number of recalibrations of the read/write head. Indicates a mechanical malfunction.
• Reallocation Events Count:Logs every attempt to move sectors.
• Current Pending Sector Count:Indicates the number of unstable sectors waiting to be moved.
• Uncorrectable Sector Count:The number of bad sectors that could not be automatically repaired.
• Write Error Rate:The number of write errors that occurred.
• Disk Shift:Indicates whether an imbalance of the disks has formed.
• Soft Read Error Rate:The number of data that was incorrectly classified by the operating system.
• G-Sense Error Rate:The shock sensor, measures the violent shocks or vibrations during operation. Excessive shocks can cause the read/write head to touch the disks mechanically. A failure of the hard disk would be the result.
• Load Friction:An internal value that measures the frictional resistance when moving the read/write head.
• Torque Amplification Count:The number of times the torque from the disk motor is readjusted.

Purely statistical values that do not directly reflect the health of the hard disk:

• Loaded Hours:Indicates how long the disk was under full load.
• Start/Stop Count:The number of start/stop operations of the drive.
• Power On Hours Count:Counts the operating hours of the drive.
• Load/Unload Cycle Count:The number of parking operations of the read/write unit. During longer pauses, the read/write head parks outside the disk range to avoid contact with the disk surface in case of vibrations.
• Read Channel Margin:Indicates how much of the bandwidth is used on average during read operations.
• Device Power Cycle Count:Statistics on how often the drive has been turned on and off.
• Power-Off Retract Cycle:Logs how often the drive has been turned off.
• Load/Unload Retry Count:Logs how often the read/write head has changed position.
• Load-in Time:Logs how long the read/write head was not parked in the parking zone.
• GMR Head Amplitude:The value of the travelled path of the read/write head during a movement.

The QNAP NAS reports when S.M.A.R.T. tests exceed the threshold values defined by the hard disk drive manufacturers and issues corresponding warning messages. Detailed information on individual S.M.A.R.T. values and the individual threshold values for each hard disk model are provided by the hard disk manufacturers. More details about the testing possibilities of the hard drives in your QNAP NAS