Hello, I have a problem with all my PCIe USB3.0 controllers running on Debian 10.3 64x - kernel 4.19.0-8 and the backports kernel 5.3.x They all have diffrent chipsets: VLI805, uPD720201, ASM1042A (latest firmware). I got on all those controllers the same issue: I only get 60-80MB/s write speed to the USB 3.0 SSD. The transfer speed is not steady if i can trust "nmon". Only bursts of data geting transfered. Then it sits in idle for about 3 seconds and does nothing. I recorded a video: https://www.youtube.com/watch?v=wXipqVX1RnQ&feature=youtu.be I'm getting 300MB/s write speed on windows. I have no issue with the read speed (300MB/s) on Debian. I already tried follow: - blacklisted uas -> lsblk didn't even show the USB3.0 SSD - kernel parameters : iommu=soft intel_iommu=off pci=nomsi -> didn't change anything Tested on follow hardware: CPU: 2x Intel Xeon L5640 MB1: Tyan S7012 (EOL, latest BIOS) MB2: Supermicro X8DTH-I (EOL, latest BIOS) SSD(internal): 2x Adata SU800 1TB (SATAII AHCI) (software raid 1 mdadm) SSD(usb): 2.5" enclosure - Samsung 850 Evo 256GB (latest firmware on enclosure and ssd) It is old hardware, i know that, but i never had a issue like this on linux. All old hardware that i had run flawless on linux even when there was no drivers for windows anymore. Maybe this is a bug. But i need to be sure. Do you need more information? Just tell me. Thanks alot, Patrick
