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The terms "Typical" and "Max" are used throughout this specification with the following meanings:
Typical. The average of the drive population tested at nominal environmental and voltage con-
ditions.
Max. The maximum value measured on any one drive over the full range of the environmental
and voltage conditions. (See Section 6.4, "Environment" on page 45 and Section 6.5, "DC
Power Requirements" on page 47.
Seek time is measured from the start of the motion of the actuator to the start of a reliable read or write
operation. "Reliable read or write" implies that error correction/recovery is not used to correct arrival pro-
blems. 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 (without command overhead, including settling)
Function
Read (80 GB – 180 GB models)
Read (30 GB & 60 GB models)
Write (80 GB – 180 GB models)
Write (30 GB & 60 GB models)
Read (Quiet Seek mode)
Write (Quiet Seek mode)
Figure 6. Full stroke seek time
Full stroke seek is measured as the average of 1000 full stroke seeks with a random head switch from
both directions (inward and outward).
4.4.2.3 Head switch time (Head skew)
72 kTPI
Figure 7. Head switch time
Head switch time is defined as the amount of time required by the fixed disk to complete a seek of the
next sequential track after reading the last sector in the current track
The measuring method is given in 4.4.5 "Throughput" on page 16.
max.
Σ (max. + 1 – n) (Tn
+ Tn
in
n=1
(max. + 1) (Tn
+ Tn
in
Typical (ms)
14.7
15.1
15.7
16.1
32.5
33.5
Head switch time - typical (ms)
Deskstar 180GXP hard disk drive specifications
)
out
)
out
Max (ms)
17.7
18.1
18.7
19.1
35.5
36.5
1.4
13
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