I have never done RAID over USB, but have done various JBOD setups using SCSI. I think the general idea is that USB having such an easily disconnected connector plus the latency overhead on translating SATA to USB to SATA again means you have a higher chance of corruption. SCSI setups typically have connectors with locking mechanisms to prevent easy disconnection.

If eSATA is an option it might be better for the performance and it has a latching mechanism to prevent easy disconnection. You can get a 2-port eSATA PCI card for about 50 bucks.

It will be perfectly reliable for a while. You’ll grow to rely on it, stop thinking about it. And then one day half your drives will suddenly be gone. You won’t know why, you won’t know how to fix it. Your raid set will already be broken. Your data will be gone.

Don’t plug and play with your data.

Its great until something overloads the USB bus or you just have a random driver reset cause it to reload, and you hear that disconnect/reconnect noise while something was writing to the array.

I tried it with a 4 bay USB 3.2 chassis over USC-C using zfs raidz, constantly had issues with the array just dying and needing to bring it back online manually many times per day. It never got better and latency was an issue too.

Move all drives to a single 8 port pcie card and it worked without issue for years.

Not worth the hassle and expense.