Low Power Idle Mode; Transition Time; Function; Attributes - IBM IC25N020ATDA04 - Travelstar 20 GB Hard Drive Specifications

11.6.3 Low Power Idle Mode

Power consumption is 60–65% less than that of Performance Idle mode. The heads are unloaded on the
ramp, however the spindle is still rotated at the full speed. Recovery time to Active mode is about 300 ms.

11.6.4 Transition Time

The transition time is dynamically managed by users recent access pattern, instead of fixed times. The
ABLE-3 algorithm monitors the interval between commands instead of the command frequency of
ABLE-2. The algorithm supposes that next command will come with the same command interval distri-
bution as the previous access pattern. The algorithm calculates the expected average saving energy and
response delay for next command in several transition time case based on this assumption. And it selects
the most effective transition time with the condition that the calculated response delay is shorter than the
value calculated from the specified level by Set Feature Enable Adaptive Power Management command.
The optimal time to enter Active Idle mode is variable depending on the recent behavior of the user. It is
not possible to achieve the same level of Power savings with a fixed entry time into Active Idle because
every user's data and access pattern is different. The optimum entry time changes over time.
The same algorithm works for entering into Low Power Idle mode and Standby mode, which consumes
less power but need more recovery time switching from this mode to Active mode.
11.7 S.M.A.R.T. Function
The intent of 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 perfor-
mance 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 after-market products.

11.7.1 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.

11.7.2 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
Travelstar 48GH, 30GN & 15GN hard disk drive specifications
86