Just a little more info to what @Elijah_Baley and @jjrjr1 provided.
Although unlike Elijah I have zero start up issues with running Drivepool on my main system, I too have a second system running a further pool also linked to Plex but only because my first server bays are full.
That said i just purchased an 8 bay DAS attached via USB and am currently in the process of moving the drives from the second server over to that. I can honestly say that performance via USB is great. (My first usage of USB drives in DrivePool since I joined the early alpha of the program.)
Shout out if you get any issues I’m sure myself Elijah or JJR will be happy to help you out. Plus Chris (Drashna) on the Stablebit support forums is one of the friendliest helpful guys I have ever known.
