WereCat

Yes, caching was disabled. Done again in reverse order, no time for the USB stick to cool down as I've popped it right into another device when it finished on the one before. And yes, the same USB stick I've tested with before.

• Zen3 Fedora41 PC - 5min 25s
• Zen4 Fedora41 Laptop - 3min 31s
• Zen1 Windows PC - 2min 19s

single 4.4GB video file

• Zen1 based Windows PC - 2min 10s (could unmount right after progress finished)
• Zen4 based Fedora41 laptop - 3min 1s (progress finished within 1min but then took 2min to unmount)
• Zen3 based Fedora41 PC - 5min 16s (progress finished within 20s but took almost 5min to unmount)

No it did not get warm at all because it was barely doing anything. But so that I'm fair I've borrowed different USB 3.2 Gen1 drive and tested also with my Fedora Laptop.

single 4.4GB video file

• Zen1 based Windows PC - 2min 10s (could unmount right after progress finished)
• Zen4 based Fedora41 laptop - 3min 1s (progress finished within 1min but then took 2min to unmount)
• Zen3 based Fedora41 PC - 5min 16s (progress finished within 20s but took almost 5min to unmount)

Thanks but that does not solve my problem. I'm not looking for alternative. If someone hands me USB drive to copy files for him I won't be able to use "LocalSend".

As I've already mentioned, sync does absolutely nothing. The copy took so long that the sync command exited 4 times while the files were still transfering and were nowhere near finishing. Regarding the watch -d grep -e Dirty: -e Writeback: /proc/meminfo command, I did not mention it in this thread but I did try it and yes, there was some almost 900k kB of data in the "Dirty" buffer that went up and down constantly even after I've disabled the caching.

it just finished, 4h for 40GB (6 files)

I'm copying 6 video files that are 40GB total and it's been over 3h now and still not finished so it's not just a lot of small files. It's just slow as hell in general. Yes, the USB is 3.0 connected to 3.0 port verified it's actually running at 3.0 bus. No, it's not fault of the USB drive as this takes around 30min from USB 2.0 on Windows 10. Yes, I've tried Fat32, exFAT and NTFS... I couldn't care less about ext4 for this particular use case so it's not relevant and I haven't tried it yet because I'm still stuck copying. Not sure what rsync does different, I just use standard CTRL+C/CTRL+V copy/paste that I expect to work flawlessly in 2025. No idea why I would want to use command line for copying files to USB drive. This seems like an ongoing problem for over 10 years from what I've been looking at trying to find solution, I found none that worked yet, just the same comments I'm getting here mostly.

Still going...

Now down to 9MB/s and still going down

EDIT: 12 min later...

I'm aware of these programs but they are just a way around the problem and not a solution. Besides they have their own limitations... I can't use KDE Connect because it does not work on my network because I run 3 routers in one network and would have to be connected to the same router which is not possible... Because of the reason why I need to run 3 routers

For sanity check I've tried.

Bus 004 Device 004 and it's USB 3.0 as it should be.

Also I've disabled caching and I'm now copying 6 video files at only just 15MB/s (and it's slowing down, byt the time I went to make screenshot for this post it dropped again). And it's quite a bit slower than on Windows still.

I'm using USB 3 10Gbps on my Linux system. The USB stick is USB 3-1.0 and the Windows PC only has USB 2.0 so it should be the slowest but it's actually several times faster.