Hitachi 7K320 Specifications - Page 19

Mechanical positioning - performance

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4.4.2 Mechanical positioning 7K320 SATA OEM Specification 4.4.2.1 Average seek time (including settling) Command Type Typical (ms) Read/Write 12 Table 5. Mechanical positioning performance Max. (ms) 18 Typical and Max. are defined throughout the performance specification 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 6.1, "Environment" on page 23 and section 6.2, "DC power requirements" on page 25) 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.  (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 4.4.2.2 Full stroke seek Command Type Read Write Table 6. Full stroke seek time Typical (ms) 20.0 22.0 Max. (ms) 27.0 29.0 Full stroke seek time in milliseconds is the average time of 1000 full stroke seeks. 4.4.2.3 Single track seek time (without command overhead, including settling) Command Type Read Write Table 7. Single track seek time Typical (ms) 1.0 1.1 Maximum (ms) 2.0 2.2 Single track seek is measured as the average of one (1) single track seek from every track in both directions (inward and outward). 4.4.2.4 Average latency Rotational Speed (RPM) 7200 Table 8. Latency time Time for one revolution (ms) 8.3 Average Latency (ms) 4.2 Page 19 of 176

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7K320 SATA OEM Specification
Page 19 of 176
4.4.2
Mechanical positioning
4.4.2.1
Average seek time (including settling)
Command
Type
Typical (ms)
Max. (ms)
Read/Write
12
18
Table 5. Mechanical positioning performance
Typical and Max. are defined throughout the performance specification 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 6.1, "Environment" on page 23 and section 6.2, "DC power
requirements" on page 25)
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.
(max. + 1 – n)(Tn
in
+ Tn
out
)
n=1
Weighted Average = ––––––––––––––––––––––––––––
(max. + 1)(max)
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
4.4.2.2
Full stroke seek
Command
Type
Typical (ms)
Max. (ms)
Read
20.0
27.0
Write
22.0
29.0
Table 6. Full stroke seek time
Full stroke seek time in milliseconds is the average time of 1000 full stroke seeks.
4.4.2.3
Single track seek time (without command overhead, including
settling)
Command
Type
Typical (ms)
Maximum (ms)
Read
1.0
2.0
Write
1.1
2.2
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).
4.4.2.4
Average latency
Rotational Speed
(RPM)
Time for one revolution
(ms)
Average Latency
(ms)
7200
8.3
4.2
Table 8. Latency time