Here is another option for a server. Install the server OS onto a uSD card, then hook a USB SSD to a USB 3 port for your data. This doesn’t involve messing around with the RPi4 to make it boot into a USB device.
On a server, the uSD with the OS is utilized to boot up the server, and start your services. Such as ssh samba minidlna, etc. Once that occurs, the server basically sits there and idles waiting for a service request for one of the services. What I am trying to get at is once booted up, everything runs out of RAM. The only time the uSD gets involved is when writing to logs, and other house keeping. So for the most part it doesn’t matter how fast the uSD is or isn’t. Since the data is on a USB SSD, data transfer is done at USB SSD speed. Plus, if the OS is on it’s own device, if the OS gets corrupted, the data is totally separated from the OS, so restoring the OS is much easier. With uSDs being so cheap, for a sever, I usually make a second install of the OS and make a backup OS device. If something happens to the OS, ten seconds to install the backup uSD and you’re back in business.
This separates your OS from your data. Since all data is on the external storage device, it is more portable. Meaning you can remove the data from one device, and move it to another device. It also makes it easier to backup your data with rsync because all the data is in one place. I always buy a second USB SSD storage device that is the same size of the data SSD. Then backup amounts to plugging in the Backup SSD, mounting it, and running rsync.
This is discussed this manual on github. This will be displayed in a very basic github viewer, click on download and it will be displayed in a browser pdf viewer where one can save or print the instructions.
@linesma
Sorry I went off topic here. If you want, I can make this a separate Topic.
Pudge