How to Test the Max Speed of a Flash Drive

Not all flash drives are created equal: some read and write faster.
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USB flash drive performance testing programs can settle the question of how fast a drive performs in real-world settings. The performance testing program, which is run on a computer, measures a flash drive's read and write speeds. Flash drives, also referred to as thumb drives and jump drives, are portable solid state data storage devices that connect to computers and other devices through the widely supported USB connection standard (References 1 and 2).

1 Understanding Read and Write Speed

Unlike cars which have a single measurable maximum travel speed, flash drive speed is rated in two ways: how quickly it can write data to the device and how quickly it can read data already stored on the device. The drive's read and write speeds are independent of each other, and one drive may be able to write faster but read slower compared to another drive.

2 Rating a Flash Drive's Speed

Flash drive speed is measured in MBps. For example, a flash drive that reads 20MBps is twice as fast as as a drive that reads at 10MBps. The storage devices vary in speed performance between models, which can cut data transfer times into fractions when using faster drives over slower drives. Write speeds are typically lower than read speeds in a performance test. Some manufacturers rate flash drive speed using the CD-ROM transfer speed system which divides the transfer speed by 150KBps. For example, a 20X flash drive transfers data around 3MBps.

3 Preparing a Drive for a Speed Test

Some flash drive speed test programs will clear the device's stored data to provide the most accurate performance results: back up data stored on a flash drive before running a performance test. The computer running the performance test should be running at least the same USB hardware revision as the flash drive. The USB standard is backward and forward compatible between generations, but a slower USB port can negatively affect a flash drive's performance. For example, the USB 3.0 standard can transfer 640 megabytes per second, ten times faster than the USB 2.0 standard. A USB 3.0 flash drive designed to run faster than 64MBps can't be adequately tested on a USB 2.0 port because the port is a performance bottleneck.

4 Running a Testing Program

USB flash performance rating programs will run a set of conditional tests to gauge the device's performance under different conditions. In addition to having different read and write speeds, the device will also perform faster if transferring a few large files as opposed to many small files. Various free programs are available to run the tests. Check Flash can test read and write speeds for small and large files comparatively. HD_Speed measures performance in both sustained and burst data transfers. CrystalDiskMark measures performance in reading and writing one massive file, small 0.5MB files and minuscule 4K files. SpeedOut rates drive read and write speed with a contiguous large file, but doesn't require erasing data.

Dan Stone started writing professionally in 2006, specializing in education, technology and music. He is a web developer for a communications company and previously worked in television. Stone received a Bachelor of Arts in journalism and a Master of Arts in communication studies from Northern Illinois University.