There are currently four speed modes defined by USB 3.1 and USB 2.0 specification. They are SuperSpeed Plus (SSP), SuperSpeed (SS), Hi-Speed (HS) and Full-Speed (FS).
The SuperSpeed Plus mode (appended in USB 3.1) has a theoretical transfer rate of 10Gbps. It’s commonly known as USB 3.1 Gen 2 while SuperSpeed or USB 3.1 Gen 1 (previously known as USB 3.0) has a bandwidth of 5Gbps. USB 2.0 is still widely used; it delivers both Hi-Speed and Full-Speed mode that operate at 480Mbps and 12Mbps respectively. (Note: the unit is in bits per second.)
When taken account protocol overheads, latency and flow control, the fastest USB 3.0 or USB 3.1 Gen 1 device should run at near 450Mbytes per second whereas a USB 3.1 Gen 2 device, in best case scenario, should perform at 1.1Gbytes per second in applications. During Gen 2 mode, overhead is reduced from 20% to just 3% with the USB 3.1’s new 128b/132b encoding scheme; hence, you see better effective throughput.
To illustrate how fast USB 3.0 is in real-world scenarios, we plotted a dozen storage devices’ benchmark data in bar graphs so you can easily tell the performance leader in each storage peripheral subcategory. Results are shown in megabytes per second. Our current testbed is a late-2014 Apple MacBook Pro Retina running Windows 10.
This benchmark was taken from our round-up of some of the fastest 128GB USB 3.0 flash drives, which are best for bulk file transfer (e.g. large media file transfers, ISO backups). In this test, we’ve included Corsair Flash Voyager GS, Kingston HyperX Savage 3.0, Lexar JumpDrive P20 and Sandisk Extreme PRO 3.0 for comparison.
Here, we selected 4 mini 64GB USB 3.0 drives that are targeted at users who value drive dimensions over speed. They include the Kingston DT Micro 3.1, Sandisk Ultra Fit 3.0, Silicon Power Jewel J06, Transcend JetFlash 710 and Verbatim Mini Metal. All four are also designed to stay plugged to a tablet, laptop and alike as a secondary storage.
We tested a number of traditional self-powered desktop drives as well as enclosures including ioSafe SoloPRO (fireproof), LaCie 2Big RAID, Seagate GoFlex Desk, SIIG USB 3.0 Dock and Thermaltake BlacX 5G USB 3.0 Case.