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

swapjim

Member
Nov 16, 2015
101
1
81
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

Platinum Member
Jan 27, 2022
2,167
751
96
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

Member
Nov 16, 2015
101
1
81
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

Platinum Member
Jan 27, 2022
2,167
751
96
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.
 

ASK THE COMMUNITY