Hitachi 7K250 Specifications - Page 30

Full stroke seek time without command overhead, including settling, 4.2.3, Head switch time - 250gb

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The terms "Typical" and "Max" are used throughout this document and are defined as follows: Typical The 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 6.2, "Environment" on page 27 and Section 6.3, "DC power require- ments" on page 29 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. A reliable read or write implies that error correction or recovery is not used to correct arrival problems. The average seek time is measured as the weighted average of all possible seek combinations. max Σ (m10 n)(Tnin + Tnout) n=1 Weighted Average (max + 1)(max) where max n Tnin Tnout = Maximum seek length = Seek length (1 to max) = Inward measured seek time for an n track seek = Outward measured seek time for an n track seek 4.4.2.2 Full stroke seek time (without command overhead, including settling) Table 6: Full stroke seek time Function Read 120-250GB 40-80GB Write 120-250GB 40-80GB Read (Quiet Seek mode) Write (Quiet Seek mode) Typical (ms) 14.7 15.1 15.7 16.1 32.5 33.5 Max (ms) 17.7 18.1 18.7 19.1 35.5 36.5 Full stroke seek is measured as the average of 1,000 full stroke seeks with a random head switch from both directions (inward and outward). 4.4.2.3 Head switch time (head skew) Table 7: Head switch time 87/90/93.5 KTPI Head switch time-typical (ms) 1.4 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 19. Deskstar 7K250 Hard Disk Drive Specification 16

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Deskstar 7K250 Hard Disk Drive Specification
16
The terms “Typical” and “Max” are used throughout this document and are defined as follows:
Typical
The 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 6.2, “Environment” on page 27 and Section 6.3, “DC power require-
ments” on page 29 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. A
reliable read or write implies that error correction or recovery is not used to correct arrival problems. The average
seek time is measured as the weighted average of all possible seek combinations.
max
Σ
(m10 n)(Tnin + Tnout)
n=1
Weighted Average =
––––––––––––––––––––––––––––
(max + 1)(max)
where
max
= Maximum seek length
n
= Seek length (1 to max)
Tnin
= Inward measured seek time for an n track seek
Tnout
= Outward measured seek time for an n track seek
4.4.2.2
Full stroke seek time (without command overhead, including settling)
Full stroke seek is measured as the average of 1,000 full stroke seeks with a random head switch from both direc-
tions (inward and outward).
4.4.2.3
Head switch time (head skew)
Head switch time is defined as the amount of time required by the fixed disk to complete a seek of the next sequen-
tial track after reading the last sector in the current track
The measuring method is given in 4.4.5, “Throughput” on page 19.
Table 6: Full stroke seek time
Function
Typical (ms)
Max (ms)
Read
120-250GB
14.7
17.7
40-80GB
15.1
18.1
Write
120-250GB
15.7
18.7
40-80GB
16.1
19.1
Read (Quiet Seek mode)
32.5
35.5
Write (Quiet Seek mode)
33.5
36.5
Table 7: Head switch time
Head switch time-typical
(ms)
87/90/93.5 KTPI
1.4