Editing USB flash drive (section)

==File transfer speeds==
{{confusing section|date=October 2024}}
Transfer speeds are technically determined by the slowest of three factors: the USB version used, the speed in which the USB controller device can read and write data onto the flash memory, and the speed of the [[Bus (computing)|hardware bus]], especially in the case of add-on USB ports.

USB flash drives usually specify their read and write speeds in megabytes per second (MB/s); read speed is usually faster. These speeds are for optimal conditions; real-world speeds are usually slower. In particular, circumstances that often lead to speeds much lower than advertised are transfer (particularly writing) of many small files rather than a few very large ones, and mixed reading and writing to the same device.

In a typical well-conducted review of a number of high-performance USB&nbsp;3.0 drives, a drive that could read large files at 68&nbsp;MB/s and write at 46&nbsp;MB/s, could only manage 14&nbsp;MB/s and 0.3&nbsp;MB/s with many small files. When combining streaming reads and writes the speed of another drive, the drive could read at 92&nbsp;MB/s and write at 70&nbsp;MB/s, was 8&nbsp;MB/s. These differences differ radically from one drive to another; some could write small files 10% faster than for large ones. The examples given are chosen to illustrate extremes.<ref>[http://www.tomshardware.com/reviews/usb-3.0-thumb-drive-flash-drive%2C2900.html Tom's Hardware: Nine USB 3.0 Flash Drives For Road Warriors] {{Webarchive|url=https://web.archive.org/web/20121017161743/http://www.tomshardware.com/reviews/usb-3.0-thumb-drive-flash-drive,2900.html |date=2012-10-17 }}, 26 April 2011</ref>