IBM DBCA-203240, Технические характеристики

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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 con-
dition. 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 attri-
butes. 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 relation-
ship 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 attri-
bute 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.
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O E M Specifications of DBCA-2xxxxx 2.5 inch H D D