Deskstar 7K400 Hard Disk Drive specification
17
4.5.4 Data transfer speed
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Instantaneous disk-buffer transfer rate (Mbyte/s) is derived by the following formula:
512 (Number of sectors on a track) (revolutions per second)
Note:
The number of sectors per track will vary because of the linear density recording.
•
Sustained disk-buffer transfer rate (Mbyte/s) is defined by considering head/cylinder change time for read opera-
tion. This gives a local average data transfer rate. It is derived by the following formula:
(Sustained Transfer Rate) = A/(B+C+D) where
A = 512 (number of data sectors per cylinder)
B = (number of Surfaces per cylinder – 1) (head switch time)
C = cylinder change time
D = (number of surfaces) (time for one revolution)
•
Instantaneous buffer-host transfer rate (Mbyte/s) defines the maximum data transfer rate on the AT Bus. It also
depends on the speed of the host.
The method of measurement is given in 4.5.5, “Throughput” on page 18.
Table 11: Data transfer speed
Data transfer speed
(Mbytes/sec)
Disk-Buffer transfer (Zone 0)
Instantaneous - typical
72.1
Sustained - read typical
61.5
Disk-Buffer transfer (Zone 29)
Instantaneous - typical
34.9
Sustained - read typical
29.8
Buffer - host (max)
133 (PATA), 150 (SATA)
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