Note that Ceph only supports 64-bits ARM, not 32-bits ARM. They removed binaries for the latter from their website, and the armhf port in Debian has a critical bug if you have non-armhf hosts in your cluster. https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=961481
Fortunately the Odroid HC4 is 64-bits, unlike its predecessors (HC1 and HC2).
Fortunately the Odroid HC4 is 64-bits, unlike its predecessors (HC1 and HC2).