Hitachi HDS723020BLA642 manual Mechanical positioning, Average seek time including settling

Typical Max.

7K200 SATA OEM Specification

4.4.2Mechanical positioning

4.4.2.1 Average seek time (including settling)

Command Type	Typical (ms)
Read	10
Write	11

Table 5. Mechanical positioning performance

Max. (ms)

16

17

Typical and Max. are defined throughout the performance specification as follows:

Average of the drive population tested at nominal environmental and voltage conditions. Maximum value measured on any one drive over the full range of the environmental and voltage conditions. (See section 6.1, "Environment" on page 26 and section 6.2, "DC power requirements" on page 28)

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 correct arrival problems. The Average Seek Time is measured as the weighted average of all possible seek combinations.

max.

Σ (max. + 1 – 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

4.4.2.2Full stroke seek

Command Type	Typical (ms)	Max. (ms)
Read	18.0	30.0
Write	19.0	31.0

Table 6. Full stroke seek time

Full stroke seek time in milliseconds is the average time of 1000 full stroke seeks.

4.4.2.3Single track seek time (without command overhead, including settling)

Command Type	Typical (ms)	Maximum (ms)
Read	1.0	4.0
Write	1.2	4.5

Table 7. Single track seek time

Single track seek is measured as the average of one (1) single track seek from every track in both directions (inward and outward).

4.4.2.4Average latency

Rotational Speed	Time for one revolution	Average Latency
(RPM)	(ms)	(ms)
7200	8.3	4.2

Table 8. Latency time

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