Buffering Operation (Lookahead/Write Cache) - IBM DDRS-39130 - Ultrastar 9.1 GB Hard Drive Specifications

Sustained disk-buffer transfer rate (Mbyte/sec) is defined by considering head/cylinder change time. This
gives a local average data transfer rate. It is derived by:
(Sustained Transfer Rate) = A/ ( B + C + D )
A = (Number of data sectors per cylinder) * 512
B = ((# of Surface per cylinder) - 1) * (Head switch time)
C = (Cylinder change time)
D = (# of Surface) * (One revolution time)
Instantaneous Buffer-Host Transfer Rate (Mbyte/sec) defines the maximum data transfer rate on SCSI
Bus. It also depends on the speed of the host.
The measurement method is given in 3.4.7, "Throughput" on page 15.

3.4.6 Buffering Operation (Lookahead/Write Cache)

At shipment, the total 384K bytes of the buffer is divided into 6 segmented blocks.
The segment size can be changed by Mode Page 8. See 7.9.9, "Page 8 (Caching Parameters)" on page 107
for details.
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O E M Spec. of DDRS-3xxxx