I used to run a 5 node Ceph cluster on a bunch of ODROID-HC2's [0]. Was a royal pain to get installed (armhf processor). But once it was running it worked great. Just slow with the single 1Gb NIC.
Was just a learning experience at the time.
[0] https://www.hardkernel.com/shop/odroid-hc2-home-cloud-two/