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4.4.2 Mechanical positioning
4.4.2.1 Average seek time (including settling)
Command Type
Read
Write
Figure 9. Mechanical positioning performance
Typical and Max. are defined throughout the performance specification as follows:
Typical
Average of the drive population tested at nominal environmental and voltage conditions.
Max.
Maximum value measured on any one drive over the full range of the environmental and
voltage conditions. (See section 6.1, "Environment" on page 23 and section 6.2, "DC power
requirements" on page 25)
The seek time is measured from the start of motion of the actuator to the start of a reliable read or write
operation. A reliable read or write operation implies that error correction/recovery is not employed to cor-
rect arrival problems. The Average Seek Time is measured as the weighted average of all possible seek
combinations.
Weighted Average = ––––––––––––––––––––––––––––
Where: max.
= maximum seek length
n
= seek length (1-to-max.)
Tn
= inward measured seek time for an n-track seek
in
Tn
= outward measured seek time for an n-track seek
out
4.4.2.2 Full stroke seek
Command Type
Read
Write
Figure 10. Full stroke seek time
Full stroke seek time in milliseconds is the average time of 1000 full stroke seeks.
max.
Σ (max. + 1 – n)(Tn
+ Tn
in
n=1
(max. + 1)(max)
Typical (ms)
23.0
24.0
Hitachi Travelstar 60GH & 40GN hard disk drive specifications
Typical (ms)
12
14
)
out
Max. (ms)
30.0
31.0
15
Max. (ms)
16
17
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