Attribute
Attributes are the specific performance or calibration parameters that are used in analyzing the status of the HDD. Attributes are selected by the device manufacturer based on that attributeÆs ability to contribute to the prediction of degrading or fault conditions for that particular device. The specific set of attributes being used and the identity of these attributes is vendor specific and proprietary.

Attribute value
Attribute values are used to represent the relative reliability of individual performance or calibration attributes. The valid range of attribute values is from 1 to 253 decimal. Higher attribute values indicate that the analysis algorithms being used by the device are predicting a lower probability of a degrading or fault condition existing. Accordingly, lower attribute values indicate that the analysis algorithms being used by the device are predicting a higher probability of a degrading or fault condition existing.

Attribute threshold
Each attribute value has a corresponding attribute threshold limit which is used for direct comparison to the attribute value to indicate the existence of a degrading or fault condition. The numerical value of the attribute thresholds are determined by the device manufacturer through design and reliability testing and analysis. Each attribute threshold represents the lowest limit to which its corresponding attribute value can be equal while still retaining a positive reliability status. Attribute thresholds are set at the device manufacturerÆs factory and cannot be changed in the field. The valid range for attribute thresholds is from 1 through 253 decimal.

Threshold exceeded condition (T.E.C.)
If one or more attribute values are less than or equal to their corresponding attribute thresholds, then the device reliability status indicates an impending degrading or fault condition.