User manual

- Hitachi hard disk drive specifications –
20
4.5.2 Mechanical positioning
4.5.2.1 Average seek time (without command overhead, including settling)
Command Type
1 Disk model
2 Disk model
Typical (ms)
Max (ms)
Typical (ms)
Max (ms)
Read
14.0
14.7
8.5
9.2
Write
15.0
15.7
9.5
10.2
Read (Quiet Seek mode)
14.0
14.7
14.0
14.7
Write (Quiet Seek mode)
15.0
15.7
15.0
15.7
Table 9 Mechanical positioning performance
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 conditions.
Max. The maximum value measured on any one drive over the full range of the environmental and voltage
conditions. (See Section 6.2, “Environment” on page 28 and Section 6.3, “DC Power Requirements” on
page 30.)
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
problems. The average seek time is measured as the weighted average of all possible seek combinations.
max.
(max. + 1 – n) (Tn
in
+ Tn
out
)
n=1
Weighted Average =
__________________________________________________
(max. + 1) (Tn
in
+ Tn
out
)
where: max = maximum seek length
n = seek length (1 to max)
Tn
in
= inward measured seek time for an n-track seek
Tn
out
= outward measured seek time for an n-track seek