Very specific setup, needing very specific advisory

I've got a homelab here with two servers. One server takes only 2.5" drives, and the other takes 3.5" (+2.5" with an adapter) drives. Of course, the one with the 2.5" drives is my main server with all my vms on it, which makes it very cost efficient, but the second server with 3.5" drives is for a NAS. Unfortunately with this setup I believe I cannot use ceph (I tried, its a massive hassle with a…