How is the internal transfer rate of disk drives defined?

A.
Speed at which data moves from the read/write head to the platter

B.
Speed at which data moves from a platter’s surface to the internal buffer

C.
Speed at which data moves from internal buffer to the host interface

D.
Speed at which data moves from the innermost cylinder to the read/write head

Explanation:
Data Transfer Rate

The data transfer rate (also called transfer rate) refers to the average amount of data per unit time
that the drive can deliver to the HBA. In a read operation, the data first moves from disk platters to
R/W heads; then it moves to the drive’s internal buffer. Finally, data moves from the buffer through
the interface to the host HBA. In a write operation, the data moves from the HBA to the internal
buffer of the disk drive through the drive’s interface. The data then moves from the buffer to the
R/W heads. Finally, it moves from the R/W heads to the platters. The data transfer rates during the
R/W operations are measured in terms of internal and external transfer rates, as shown in the
slide.
Internal transfer rate is the speed at which data moves from a platter’s surface to the internal
buffer (cache) of the disk. The internal transfer rate takes into account factors such as the seek
time and rotational latency. External transfer rate is the rate at which data can move through the
interface to the HBA. The external transfer rate is generally the advertised speed of the interface,
such as 133 MB/s for ATA. The sustained external transfer rate is lower than the interface speed.
EMC E10-001 Student Resource Guide. Module 2: Data Center Environment