The Drive In-Depth; About Hi-Speed Usb 2.0 - Acomdata EXTERNAL E5 HARD DRIVE USB 2.0 User Manual

The Drive In-Depth

About Hi-Speed USB 2.0

Your AcomData Drive is equipped with a Hi-Speed USB 2.0
interface. (USB stands for "Universal Serial Bus.") USB 2.0 has a
maximum interface transfer rate (i.e. bandwidth) of 480 Mbps
(Megabits per second). That's 40 times faster than the earlier
standard, USB 1.1, which has a bandwidth of 12 Mbps).
Performance in day-to-day use will depend on many factors,
including: CPU utilization; file system overhead; the number of
active devices on the USB bus; the size, structure and number
of files being transferred, and; the speed at which other devices
can transfer data to/from the Drive. Also, as is the case with any
data I/O (input/output) technology, some bandwidth is taken up
by the protocols that structure and govern data transmissions
(this is called interface overhead). Given these and other factors,
in day-to-day use you can expect maximum, sustained transfer
rates in the mid-30s MB/s (Megabytes per second).
Note: The interface transfer rate specification of an I/O technology,
such as USB, is expressed using the bit as the base unit (e.g. Mbps)
because this is the truest way of measuring raw interface performance.
However, for the end user it is more meaningful to express day-to-day
transfer rates using the byte as the base unit (e.g. MB/s) because com-
puter files are measured in bytes (kilobytes, megabytes, etc.).
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