Mechanical Positioning; Table 6. Mechanical Positioning Performance - Hitachi HUS151473VL3800 - Ultrastar 73.4 GB Hard Drive Specifications

4.5.1 Mechanical positioning

4.5.1.1 Average seek time (including settling)
Table 6: Mechanical positioning performance
Model Command
147 GB Read
Write
73 GB Read
Write
36 GB Read
Write
"Typical" and "Max" are used throughout this document and are defined 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 8.0, "Environment" on page 31 and Section 9.0, "DC power requirements" on page 35 for
ranges.)
The seek time is measured from the start of the actuator's motion to the start of a reliable read or write operation. "Reliable
read or write" implies that error correction or recovery is not used to correct arrival problems. The average seek time is mea-
sured as the weighted average of all possible seek combinations.
Weighted average =
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
Typical (ms) Max
3.7 3.9
4.1 4.3
3.6 3.8
4.0 4.1
3.3 3.5
3.7 3.8
Max
∑
(
= max + 1 n –
n = 1
----------------------------------------------------------------------------------------------- -
(
max +
Hitachi Ultrastar 15K147 SCSI Hard Disk Drive Specification
) ( ⋅
Tnin + Tnout
) ⋅ ( )
1 max
11
)