I have built the following configuration:
- Raspberry Pi 4 2GB with original Raspberry power supply 5.1V/3A
- 2 x Samsung SSD 870 EVO 4TB connected to ASMedia USB-SATA Bridge (174c:55aa)
- LogiTech K400+ keyboard
Because a RAID 1 via USB is not possible, I use one SSD as storage and mirror the content of the SSD in regular intervals via rsync to the second SSD.
At first I booted the Raspi from a USB stick, but then the SSDs were not attached at all or only one at boot time. This has been solved since I booted the Raspi from a SD card. Since then both SSDs are available after booting.
My problem now is that (apparently) when higher load runs over the USB ports (robocopy via SMB/CIFS share to the storage SSD), the backup SSD is disconnected after some time. This SSD can only be reconnected by unplugging the USB connector and plugging it back in, then using "sudo mount -a" to mount the disk.
I also already swapped the USB ports and the disks, disabled UASP in /boot/cmdline.txt, disabled USB power limit in /boot/config.txt and I don't remember what else I tested.
When both SSDs are connected, lsusb -t -v looks like this:
After the disconnet the following is written in the dmesg:
After unplugging the USB connector and plugging it back in the following is written to dmesg:
Shortly after that the SSD is disconnected again with the following messegas in dmesg:
It would be nice if someone had a similar experience and could give me an idea how to prevent the disconnect of the backup SSD.
