Question Slow speed by USB 3.0 pen drive?

[amit.rudy]

I have bought a USB 3.0 pen drive...when i connect it to front USB 3.0 port of my desktop cabinet, in starting i get around "20MBps" transfer speed...when the transfer reaches around 40% it drops down to around 5-7MBps... when i connect the same pen drive to backside usb 3.0 ports of my cabinet(directly into the motherboard), in starting i get around 40MBps speed and after 40-50% completion it drops down to around 12-13MBps... I am conducting this test by using a single 4GB video file...the file system of pen drive is NTFS, I think something is causing the problem...im on windows 10 64bit version 1803... in device manager the drivers for usb ports are showing latest. What can i do?

 

[Grobe]

It could be a windows cache related issue.

Else - here is a video that might explain (i'm not completely sure this also tranlates to usb sticks too)

View: https://www.youtube.com/watch?v=OffzVc7ZB-o

 

[amit.rudy]

It could be a windows cache related issue.

Else - here is a video that might explain (i'm not completely sure this also tranlates to usb sticks too)

View: https://www.youtube.com/watch?v=OffzVc7ZB-o

No unfortunately i havent got answer yet!

 

[PC Tailor]

I actually agree with above, it is likely due to a buffer cache. Your OS will write to the buffer cache before writing directly to the USB.
In bigger files it won't necessarily write to the buffer cache, so you'll lose performance.

In effect once the cache is exhausted, you're then relying and limited on the speed of the disk to write directly to the USB.

Which is why you'll see it transferring big files, it's writing as quickly as the hard disk can give it.

 

[amit.rudy]

I actually agree with above, it is likely due to a buffer cache. Your OS will write to the buffer cache before writing directly to the USB.
In bigger files it won't necessarily write to the buffer cache, so you'll lose performance.

In effect once the cache is exhausted, you're then relying and limited on the speed of the disk to write directly to the USB.

Which is why you'll see it transferring big files, it's writing as quickly as the hard disk can give it.

Cant say about cache... but i have also tried copying video files of about 1.5GB, still the results were same. Anyway i found my answer through my research, the sandisk 32GB 3.0 pendrive which i have, is cheap quality pendrive. i saw YouTube videos and all people were claiming that its write speed is around 12-13MBps. Image here ---> Sandisk OTG 32GB 3.0 Pendrive . Thanks all for participating.