Question thumb drive: why the discrepancy in write speed between Crystal Mark and Windows?

[swapjim]

Crystal Mark shows around 100MB/sec write speed but when I transfer a 10GB file from my SSD (capable of doing around 500MB/sec) to the thumb drive, I get around 30MB/sec.

It's a Kingston Kyson 128GB, and the drive specs mention 60MB/sec. The Kyson at 32GB and 64GB don't list write speed in the specs.

 

[Tech Junky]

Depends on the host system, port, available space, the USB controller and the flash used in the USB drive. I have one that does SSD speeds over USB around 400mb/s and shows in the system devices as an SSD and not a portable drive.

 

[swapjim]

Nothing changed between the two tests. I used the same OS, the same port, the same USB cable, and it had the same free space (completely empty). I didn't even unmount the device.

 

[Tech Junky]

CDM doesn't give IRL speeds. I can bench an NVME gen4 drive up to 7gb/s but actual data copies tend to top out around 50% of benchmark numbers. My TB4 enclosure is where I get 3gb/s but moving files internally usually hits 1.5gb/s.

USB in general doesn't hit enormous speeds without involving actual drives being used. I have one USB enclosure that hits a gig. Flash drives though tend to be slow because they use cheap components. The total one that hits close to 400mb/s is the SanDisk extreme pro.