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USB Flash Drives Data Read and Write Speed

This article documents data read and write speeds for various flash USB drives, including some old ones.

Environment

We have tested the drives in the following environment:

Hardware: Gigabyte ZA-Z97X-SLI motherboard, Intel i3-4170 CPU 3.70 GHz and 16 GB RAM.
Various USB 3.0 ports on the back, and a couple on the front of the box (USB 2.0 and 3.0).
Software - Ubuntu 16.04 LTS running off a 120 GB Kingston SSD.

Tested USB Flash Drives

A (very) old Sony 8GB flash drive with markings SDK-USM8GL (B) 09D12KEDV on the back (if I read it right) with built-in LED activity indicator.
An old Staples 16 GB flash drive with markings USB 2.0 27988 on the back. This drive also came with a built-in LED activity indicator.
Acquired in January 2019, 32 GB Kingston DataTraveler 100 G3 with marking USB 3.1/3.0/2.0 in the packaging. I have 2 of these to test. They are without LED indicators.
Acquired in January 2019, SanDisk Ultra 16GB Micro SDHC UHS-I Card with Kingston Digital G2 USB 2.0 microSDHC Flash Memory Card Reader FCR-MRG2. This card can also be used with UGREEN USB 3.0 hub for higher speeds, see the picture of the hub below.

Below are photos showing all these drives.

USB flash drives to test data read and write speed

Formatting Drives

We can start with formatting drives using the Disks utility coming in Ubuntu. Formatting the old Sony flash drive in Overwrite existing data with zeroes (Slow) mode shows up as 6.1-5.9 MB/sec (megabytes per second), which gives us some indication of data write speed. Write speed is getting a bit slower towards partition end. Note: my experiments show that formatting speed does not change much between MBR (Compatible with all systems and devices) and GPT (Compatible with modern systems and hard disks > 2 TB) modes. I tried both with approximately the same outcome.

Formatting Sony USB flash drive: 5.9 - 6.1 megabytes per second — Formatting Sony USB flash drive: **5.9 - 6.1** megabytes per second

Formatting the Staples USB drive, which is USB 2.0, shows an improvement in write speed to 15.4 MB/s.

Formatting Staples USB flash drive: 15.4 megabytes per second — Formatting Staples USB flash drive: **15.4** megabytes per second

Formatting the newer Kingston DataTraveler USB drive, which is USB 3.0, is not much different from USB 2.0 with write speed of 15.7 MB/s.

Formatting Kingston USB flash drive: 15.7 megabytes per second — Formatting Kingston USB flash drive: **15.7** megabytes per second

Formatting SanDisk Micro SDHC cart over USB 2.0 reader: 11.2 MB/s.

Formatting SanDisk Micro SDHC cart over UGREEN USB 3.0 hub: 13.9 MB/s.

Benchmark Data Speed Testing

Ubuntu 16.04 LTS Disks utility also has a useful Benchmark disk feature, which we could use to measure read and write speeds. The following list summarizes test results for all test drives. with default test settings on sample size 10,485,760 bytes, 100 samples. MB/s below means megabytes per second.

Note: these results should be treated as approximate. I observed them fluctuate significantly (up to 20% or so) in repeated tests.

Old Sony drive, via USB 3.0 near back port: read 19.4 MB/s, write: 5.4 MB/s. Access time: 0.75 ms.
Old Sony drive, via USB 3.0 hub over near back port: read 19.4 MB/s, write: 5.4 MB/s. Access time: 0.77 ms.
Old Sony drive, via USB 3.0 front left port: read 19.4 MB/s, write: 5.4 MB/s. Access time: 0.74 ms.
Old Sony drive, via USB 2.0 front right port: read 19.4 MB/s, write: 5.4 MB/s. Access time: 0.74 ms.

Old USB 2.0 Staples drive, via USB 3.0 near back port: read 28.3 MB/s, write: 8.3 MB/s. Access time: 0.52 ms.
Old USB 2.0 Staples drive, via USB 3.0 hub over near back port: read 28.4 MB/s, write: 8.3 MB/s. Access time: 0.51 ms.
Old USB 2.0 Staples drive, via USB 3.0 front left port: read 28.5 MB/s, write: 8.3 MB/s. Access time: 0.54 ms.
Old USB 2.0 Staples drive, via USB 2.0 front right port: read 28.5 MB/s, write: 8.3 MB/s. Access time: 0.52 ms.

USB 3.1 Kingston drive 1, via USB 3.0 near back port: read 104.7 MB/s, write: 6.4 MB/s. Access time: 0.73 ms.
USB 3.1 Kingston drive 1, via USB 3.0 hub over near back port: read 115.5 MB/s, write: 7.5 MB/s. Access time: 0.48 ms.
USB 3.1 Kingston drive 1, via USB 3.0 front left port: read 105.9 MB/s, write: 6.5 MB/s. Access time: 0.63 ms.
USB 3.1 Kingston drive 1, via USB 2.0 front right port: read 45.3 MB/s, write: 5.4 MB/s. Access time: 0.67 ms.

USB 3.1 Kingston drive 2, via USB 3.0 near back port: read 106.5 MB/s, write: 6.4 MB/s. Access time: 0.70 ms.
USB 3.1 Kingston drive 2, via USB 3.0 hub over near back port: read 114.1 MB/s, write: 6.7 MB/s. Access time: 0.49 ms.
USB 3.1 Kingston drive 2, via USB 3.0 front left port: read 101.2 MB/s, write: 6.3 MB/s. Access time: 0.69 ms.
USB 3.1 Kingston drive 2, via USB 2.0 front right port: read 44.9 MB/s, write: 5.1 MB/s. Access time: 0.67 ms.

Micro SDHC card, via USB 2.0 reader, connected to USB 3.0 near back port: read 19.4 MB/s, write: 11.4 MB/s. Access time: 0.89 ms.
Micro SDHC card, via USB 2.0 reader, connected to USB 3.0 front left port: read 19.6 MB/s, write: 11.3 MB/s. Access time: 0.90 ms.
Micro SDHC card, via USB 2.0 reader, connected to USB 2.0 front right port: read 19.6 MB/s, write: 11.4 MB/s. Access time: 0.90 ms.

Micro SDHC card, via USB 3.0 hub, connected to USB 3.0 near back port: read 89.9 MB/s, write: 14.6 MB/s. Access time: 0.74 ms.
Micro SDHC card, via USB 3.0 hub, connected to USB 3.0 front left port: read 87.2 MB/s, write: 14.6 MB/s. Access time: 0.71 ms.
Micro SDHC card, via USB 3.0 hub, connected to USB 2.0 front right port: read 45.0 MB/s, write: 14.3 MB/s. Access time: 0.78 ms.

And, for comparison with SSD speeds:

1st test: Kingston 120 GB SSD: read 508.0 MB/s, write: 140.3 MB/s. Access time: 0.08 ms.
2nd test: Kingston 120 GB SSD: read 513.0 MB/s, write: 341.3 MB/s. Access time: 0.07 ms.
3rd test: Kingston 120 GB SSD: read 517.5 MB/s, write: 407.1 MB/s. Access time: 0.05 ms.

Connecting via USB 3.0 Hub

The second option in each group above: via USB 3.0 hub over near back port means that I additionally tested the drives connected to a USB 3-port hub as on the photo below, while the hub itself was connected to a USB 3.0 port on the back of my PC. This product is made by UGREEN (Ugreen Group Limited) in China and has Multiport Adapter name on the front of the box, and UGREEN USB 3.0 hub (... card reader, Black) NEW sticker on the back.

Note: the hub has a little white LED built in (see the photo below). I purchased it because I thought it indicates data transmission as built-in LEDs in some of USB drives. I was wrong. It lights at all times when connected without indicating data transmission events. This LED (or even 3 separate LEDs, one for each port) would be much more useful, if it indicated data transmission taking place.

Conclusion

Although write speeds for newer drives appear somewhat below that of an old USB 2.0 unit from Staples, read speeds are significantly better. Therefore, if we have an application that mostly reads from drive and writes little, there is a benefit of using a newer drive.

Another thing to note is that write speed during formatting shows up significantly higher, as compared to benchmark write tests. This probably means that benchmark data are a bit close to reality of having a real application writing data at random partition locations.

Connecting via a hub does not seem to slow things down at all. Some tests actually show an improvement. I don't know how to explain this. Perhaps, due to fluctuations in testing environment.

Also, a Micro SDHC card shows much better write speeds than flash drives, when connected via a USB 3.0 hub, which makes it a better candidate for write-intensive applications.

For a write-intensive application, approximate write speeds in MB/s and percentage look as follows:

SSD - 300 MB/s - 100%.
Micro SDHC card via USB 3.0 hub - 14.3 MB/3 - 5% (20 times slower than SSD).
USB 3.1 Kingston flash drive via USB 3.0 port: 6.5 MB/s - 2% (50 times slower than SSD).