IBM DTCA-24090 Hard Drive Specifications - Page 84

10.6 S.M.A.R.T. Function The intent of Self-monitoring, analysis and reporting technology (S.M.A.R.T) is to protect user data and prevent unscheduled system downtime that may be caused by predictable degradation and/or fault of the device. By monitoring and storing critical performance and calibration parameters, S.M.A.R.T devices employ sophisticated data analysis algorithms to predict the likelihood of near-term degradation or fault condition. By alerting the host system of a negative reliability status condition, the host system can warn the user of the impending risk of a data loss and advise the user of appropriate action. Since S.M.A.R.T. utilizes the internal device microprocessor and other device resources, there may be some small overhead associated with its operation. However, special care has been taken in the design of the S.M.A.R.T. algorithms to minimize the impact to host system performance. Actual impact of S.M.A.R.T. overhead is dependent on the specific device design and the usage patterns of the host system. To further ensure minimal impact to the user, S.M.A.R.T. capable devices are shipped from the device manufacturer's factory with the S.M.A.R.T. feature disabled. S.M.A.R.T. capable devices can be enabled by the system OEMs at time of system integration or in the field by aftermarket products. 10.6.1 Attributes Attributes are the specific performance or calibration parameters that are used in analyzing the status of the device. Attributes are selected by the device manufacturer based on that attribute's ability to contribute to the prediction of degrading or faulty conditions for that particular device. The specific set of attributes being used and the identity of these attributes is vendor specific and proprietary. 10.6.2 Attribute values Attribute values are used to represent the relative reliability of individual performance or calibration attributes. 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. There is no implied linear reliability relationship corresponding to the numerical relationship between different attribute values for any particular attribute. 10.6.3 Attribute thresholds 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 faulty 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 manufacturer's factory and cannot be changed in the field. The valid range for attribute thresholds is from 1 through 253 decimal. 10.6.4 Threshold exceeded condition If one or more attribute values are less than or equal to their corresponding attribute thresholds, then the device reliability status is negative, indicating an impending degrading or faulty condition. 10.6.5 S.M.A.R.T. commands The S.M.A.R.T. commands provide access to attribute values, attribute thresholds and other logging and reporting information. 76 OEM Specifications of DTCA-2xxxx 2.5 inch H D D